From fb5712f17df87bc2be127c094fd9ecc3ac0a6c97 Mon Sep 17 00:00:00 2001 From: Boris Kolpackov Date: Mon, 7 May 2018 16:20:33 +0200 Subject: Rename intro2 to intro, old intro to intro1 --- doc/cli.sh | 2 +- doc/intro.cli | 1979 +++++++++++++++++++++++++++++++------------------------- doc/intro1.cli | 1169 +++++++++++++++++++++++++++++++++ doc/intro2.cli | 1390 --------------------------------------- 4 files changed, 2270 insertions(+), 2270 deletions(-) create mode 100644 doc/intro1.cli delete mode 100644 doc/intro2.cli (limited to 'doc') diff --git a/doc/cli.sh b/doc/cli.sh index 1747730..7126f5c 100755 --- a/doc/cli.sh +++ b/doc/cli.sh @@ -49,8 +49,8 @@ html2ps -f doc.html2ps:letter.html2ps -o build2-toolchain-$n-letter.ps build2-to ps2pdf14 -sPAPERSIZE=letter -dOptimize=true -dEmbedAllFonts=true build2-toolchain-$n-letter.ps build2-toolchain-$n-letter.pdf } -gen intro2 gen intro +#gen intro1 # Auto-heading doesn't work since it is broken into multiple doc strings. # diff --git a/doc/intro.cli b/doc/intro.cli index ac43311..a90a3ae 100644 --- a/doc/intro.cli +++ b/doc/intro.cli @@ -18,7 +18,6 @@ // PDF // // @@ tree output is garbled -// @@ Install list margins missing // @@ Could we use a nicer font, seeing that we embed them? // @@ -28,1142 +27,1364 @@ // " -\h#tldr|TL;DR| +\h1#tldr|TL;DR| \ -$ bpkg create -d hello cc -created new configuration in hello/ +$ git clone ssh://example.org/hello.git +$ tree hello +hello/ +├── hello/ +│   ├── hello.cxx +│   └── buildfile +├── manifest +└── repositories.manifest -$ cd hello/ -$ bpkg add https://build2.org/pkg/1/hello/stable -added repository build2.org/hello/stable +$ cd hello +$ bdep init --config-create ../hello-gcc cc config.cxx=g++ +initializing project /tmp/hello/ +created configuration /tmp/hello-gcc/ (default, auto-synchronized) +synchronizing: + new hello/0.1.0 -$ bpkg fetch -fetching build2.org/hello/stable -2 package(s) in 1 repository(s) - -$ bpkg build hello - build libhello/1.0.0 (required by hello) - build hello/1.0.0 -continue? [Y/n] y - -libhello-1.0.0.tar.gz 100% of 2428 B 983 kBps 00m01s -fetched libhello/1.0.0 -unpacked libhello/1.0.0 +$ b +c++ hello/cxx{hello}@../hello-gcc/hello/hello/ +ld ../hello-gcc/hello/hello/exe{hello} +ln ../hello-gcc/hello/hello/exe{hello} -> hello/ -hello-1.0.0.tar.gz 100% of 1057 B 6882 kBps 00m01s -fetched hello/1.0.0 -unpacked hello/1.0.0 +$ hello/hello World +Hello, World! -configured libhello/1.0.0 -configured hello/1.0.0 +$ edit repositories.manifest # add https://example.org/libhello.git +$ edit manifest # add 'depends: libhello ^1.0.0' +$ edit hello/buildfile # import libhello +$ edit hello/hello.cxx # use libhello -c++ hello-1.0.0/cxx{hello} -c++ libhello-1.0.0/hello/cxx{hello} -ld libhello-1.0.0/hello/libs{hello} -ld hello-1.0.0/exe{hello} +$ b +fetching from https://example.org/libhello.git +synchronizing /tmp/hello-gcc/: + new libhello/1.0.0 (required by hello) + reconfigure hello/0.1.0 +c++ ../hello-gcc/libhello-1.0.0/libhello/cxx{hello} +ld ../hello-gcc/libhello-1.0.0/libhello/libs{hello} +c++ hello/cxx{hello}@../hello-gcc/hello/hello/ +ld ../hello-gcc/hello/hello/exe{hello} +ln ../hello-gcc/hello/hello/exe{hello} -> hello/ + +$ bdep fetch # refresh available versions +$ bdep status -i # review available versions +hello configured 0.1.0 + libhello ^1.0.0 configured 1.0.0 available [1.1.0] + +$ bdep sync libhello # upgrade to latest +synchronizing: + new libformat/1.0.0 (required by libhello) + new libprint/1.0.0 (required by libhello) + upgrade libhello/1.1.0 + reconfigure hello/0.1.0 -updated hello/1.0.0 +$ bdep sync libhello/1.0.0 # downgrade +synchronizing: + drop libprint/1.0.0 (unused) + drop libformat/1.0.0 (unused) + downgrade libhello/1.0.0 + reconfigure hello/0.1.0 \ -" -" -\h#warning|Warning| +\h1#guide|Getting Started Guide| + +The aim of this guide is to get you started developing C/C++ projects with the +\c{build2} toolchain. All the examples in this section include the relevant +command output so if you just want to get a sense of what \c{build2} is about, +then you don't have to install the toolchain and run the commands in order to +follow along. If at the end you find \c{build2} appealing and would like to +start using it or try the examples for yourself, you can jump straight to +\l{build2-toolchain-install.xhtml The \c{build2} Toolchain Installation and +Upgrade}. -The \c{build2} toolchain \c{0.X.Y} series are alpha releases. Interfaces -\i{will} most likely change in backwards-incompatible ways. But if you want -to start playing with it, welcome and join the \l{https://lists.build2.org -mailing list}! +One of the primary goals of the \c{build2} toolchain is to provide a uniform +interface across all the platforms and compilers. While the examples in this +document assume a UNIX-like operation system, they will look pretty similar if +you are on Windows. You just have to use appropriate paths, compilers, and +options. -Our approach to developing \c{build2} is to first get the hard parts right -before focusing on completeness. So while we might still have no support for -custom build rules, we do handle auto-generated source code (and, in -particular, headers) properly. In other words, we go depth rather than -breadth-first. As a result, there are some limitations and missing pieces, -especially in the build system. The most notable ones are: +The question we will try to answer in this section can be summarized as: -\ul| +\ +$ git clone .../hello.git && now-what? +\ -\li|Limited documentation.| +That is, we clone an existing C/C++ project or would like to create a new one +and then start hacking on it. We want to spend as little time and energy as +possible on the initial and ongoing infrastructure maintenance: setting up +build configurations, managing dependencies, continuous integration and +testing, release management, etc. Or, as one C++ user aptly put it, \"\i{All I +want to do is program.}\" -\li|No support for custom build system rules/modules.| +\h#guide-hello|Hello, World| -| -" +Let's see what programming with \c{build2} feels like by starting with a +customary \i{\"Hello, World!\"} program (here we assume our current working +directory is \c{/tmp}): -" -\h#intro|Introduction| - -The \c{build2} toolchain is a set of tools designed for building and packaging -C and C++ code (though, if it can handle C++, it can handle anything, -right?). The toolchain currently includes the \i{build system} (\c{build2}), -the \i{package manager} (\c{bpkg}), and the \i{repository web interface} -(\c{brep}). More tools, such as the \i{build robot} (\c{bbot}), are in the -works. Then there is \l{https://cppget.org/ cppget.org} (running \c{brep}) -which we hope will become \i{the C++ package repository}. - -The goal of this document is to give you a basic idea of what the \c{build2} -toolchain can do so that you can decide if you are interested and want to learn -more. Further documentation is referenced at the end of this introduction. - -The \c{build2} toolchain is self-hosted and self-packaged (and, yes, it is on -\l{https://cppget.org/ cppget.org}). It could have served as its own example, -however, before the toolchain can build itself, we have to bootstrap it (that -chicken and egg problem again). And this step wouldn't serve our goal of -quickly learning what \c{build2} is about. So, instead, we will start with a -customary \i{\"Hello, World!\"} example which you won't yet be able to try -yourself (but don't worry, complete terminal output will be shown). If at the -end you find \c{build2} appealing, you can jump straight to -\l{build2-toolchain-install.xhtml The \c{build2} Toolchain Installation and -Upgrade} (and, yes, there you get to run that coveted \c{bpkg build bpkg}). -Once the \c{build2} installation is complete, you can come back to the -\i{\"Hello, World!\"} example and try all of the steps for yourself. +\ +$ bdep new -t exe -l c++ hello +created new executable project hello in /tmp/hello/ +\ -This introduction explores the \i{consumer} side of \i{\"Hello, World!\"}. -That is, we assume that someone was kind enough to create and package the -\c{libhello} library as well as the \c{hello} program and we will learn how to -obtain and build them as well as keep up with their updates. At the end we -will also see how to write our own, \c{hello2}, program that depends on -\c{libhello}. And so, without further ado, let's begin. +The \l{bdep-new(1)} command creates a \i{canonical} \c{build2} project. In +our case it is an executable implemented in C++. -Actually, one more thing: if you have a recent enough compiler and would like -to try the new C++ Modules support, then you can instead use the modularized -variants of these packages: simply replace \c{hello} with \c{mhello} and -\c{libhello} with \c{libmhello} in the commands below. +\N|To create a library, pass \c{-t\ lib}. By default \c{new} also initializes +a \c{git} repository and generates suitable \c{.gitignore} files (pass \c{-s\ +none} if you don't want that).| -The first step in using \c{bpkg} is to create a \i{configuration}. A -configuration is a directory where packages that require similar compile -settings will be built. You can create as many configurations as you want: for -different C++ compilers, targets (\c{build2} is big on cross-compiling), -debug/release, 32/64-bit, or even for different days of the week, if you are -so inclined. Say we are in the mood for a GCC 5 release build today: +Let's take a look inside our new project: \ -$ mkdir hello-gcc5-release -$ cd hello-gcc5-release -$ bpkg create cxx config.cxx=g++-5 config.cxx.coptions=-O3 -created new configuration in /tmp/hello-gcc5-release/ +$ tree hello +hello/ +├── .git/ +├── .bdep/ +├── build/ +├── hello/ +│   ├── hello.cxx +│   ├── buildfile +│   └── testscript +├── buildfile +├── manifest +└── repositories.manifest \ -Or perhaps you are on Windows and prefer Visual Studio (running from the -Visual Studio Tools Command Prompt): +\N|While the canonical project structure is strongly recommended, especially +for new projects, \c{build2} is flexible enough to allow most commonly used +arrangements.| + +Similar to version control tools, we normally run all \c{build2} tools from +the project's source directory or one of its subdirectories, so: \ -> mkdir hello-vc14-release -> cd hello-vc14-release -> bpkg create cxx config.cxx=cl config.cxx.coptions=/O2 -created new configuration in C:\projects\hello-vc14-release\ +$ cd hello \ -One of the primary goals of the \c{build2} toolchain is to provide a uniform -build interface across all the platforms and compilers. While the following -examples use the \c{hello-gcc5-release} configuration and assume a UNIX-like -operation system, everything will work if you use \c{hello-vc14-release} (or -\c{hello-mingw-release}) on Windows. Just use appropriate paths, compilers, -and options. +While the project layout is discussed in more detail in later sections, let's +examine a couple of interesting files to get a sense of what's going on. We +start with the source file which should look familiar: -Let's discuss that last command line: \l{bpkg-cfg-create(1) \c{bpkg create}} -is the command for creating a new configuration. As a side note, if you ever -want to get help for any \c{bpkg} command, run \c{bpkg help \i{}}. To -see the list of commands, run just \l{bpkg-help(1) \c{bpkg help}} (or see -\l{bpkg(1)}). While we are at it, if you ever want to see what \c{bpkg} is -running underneath, there is the \c{-v} (essential commands) and \c{-V} (all -commands) options. And if you really want to get under the hood, use -\l{bpkg-common-options(1) \c{--verbose }}. +\ +$ cat hello/hello.cxx -After the command we have \c{cxx} which is the name of the \c{build2} build -system module. As you might have guessed, \c{cxx} provides support for the C++ -compilation. By specifying this module when creating the configuration we -configure it (yes, with those \c{config.cxx.*} variables that follow) for the -entire configuration. That is, every package that we will build in this -configuration and that uses the \c{cxx} module will by default inherit these -settings. +#include -The rest of the command line are the configuration variables for the \c{cxx} -module with \c{coptions} standing for \i{compile options} (there are also -\c{poptions} for \i{preprocess options}, \c{loptions} for \i{link options}, and -\c{libs} for extra libraries to link). +using namespace std; -There is also the \c{c} module for the C compilation. So if we were planning -to build both C and C++ projects, then we could have run: +int main (int argc, char* argv[]) +{ + if (argc < 2) + { + cerr << \"error: missing name\" << endl; + return 1; + } + cout << \"Hello, \" << argv[1] << '!' << endl; +} \ -$ bpkg create c cxx ... + +\N|If you prefer the \c{.?pp} extensions over \c{.?xx} for your C++ source +files, pass \c{-l\ c++,cpp} to the \c{new} command. See \l{bdep-new(1)} for +details on this and other customization options.| + +Let's take a look at the accompanying \c{buildfile}: + \ +$ cat hello/buildfile -The problem, of course, is that you may not know what mix of languages those -projects (or their dependencies) might use. For example, the use of C might be -an implementation detail of a C++ library. To solve this, \c{build2} provides -another module called \c{cc} which stands for \i{C-common}. So, in this -context, instead of using the \c{c} and \c{cxx} modules directly, it's a good -idea to get into the habit of using \c{cc}: +libs = +#import libs += libhello%lib{hello} +exe{hello}: {hxx ixx txx cxx}{*} $libs test{testscript} \ -$ bpkg create cc config.cxx=g++-5 config.cc.coptions=-O3 + +As the name suggests, this file describes how to build things. While its +content might look a bit cryptic, let's try to infer a couple of points +without going into too much detail (the details are discussed in the following +sections). That \c{exe{hello\}} on the left of \c{:} is a \i{target} +(executable named \c{hello}) and what we have on the right are +\i{prerequisites} (C++ source files, libraries, etc). This \c{buildfile} uses +\l{b#name-patterns wildcard patterns} (that \c{*}) to automatically locate all +the C++ source files. This means we don't have to edit our \c{buildfile} every +time we add a source file to our project. There also appears to be some +(commented out) infrastructure for importing and linking libraries (that +\c{libs} variable). We will see how to use it in a moment. Finally, the +\c{buildfile} also lists \c{testscript} as a prerequisite of \c{hello}. This +file tests our target. Let's take a look inside: + \ +$ cat hello/testscript -Notice two things about this command line: we don't need to specify the C -compiler with \c{config.c} \- \c{build2} is smart enough to figure it out -from \c{config.cxx} (or vice versa). We also used \c{config.cc.coptions} -instead of \c{config.cxx.coptions} so that the options apply to all the -C-common languages (we can still use \c{config.{c,cxx\}.*} for the -language-specific options). +: basics +: +$* 'World' >'Hello, World!' + +: missing-name +: +$* 2>>EOE != 0 +error: missing name +EOE +\ -Ok, configuration in hand, where can we get some packages? \c{bpkg} packages -come from \i{repositories}. A repository can be a local filesystem directory -or a remote URL. Our example packages come from their own remote \i{\"Hello, -World!\"} repository: \c{\l{https://build2.org/pkg/1/hello/stable/}} (go ahead, -browse it, I will wait). +Again, we are not going into detail here (see \l{testscript#intro Testscript +Introduction} for a proper introduction), but to give you an idea, here we +have two tests: the first (with id \c{basics}) verifies that our program +prints the expected greeting while the second makes sure it handles the +missing name error condition. Tests written in Testscript are concise, +portable, and executed in parallel. -Instead of scouring repository manifests by hand (I know you couldn't resist), -we can ask \c{bpkg} to interrogate a repository location for us: +Next up is \c{manifest}: \ -$ bpkg rep-info https://build2.org/pkg/1/hello/stable -warning: authenticity of the certificate for repository build2.org/hello/stable cannot be established -certificate is for build2.org, \"Code Synthesis\" -certificate SHA256 fingerprint: -FF:DF:7D:38:67:4E:C3:82:[...]:30:56:B9:77:B9:F2:01:94 -trust this certificate? [y/n] +$ cat manifest +: 1 +name: hello +version: 0.1.0-a.0.z +summary: hello executable project +license: proprietary +url: https://example.org/hello +email: you@example.org +#depends: libhello ^1.0.0 \ -The \c{bpkg} repositories are normally signed to prevent tampering with -packages. If the repository certificate is seen (in this configuration) for -the first time, \c{bpkg} will ask you to authenticate it. A good way to -authenticate a certificate is to compare the displayed fingerprint to the one -you have received earlier, for example, in an email announcement. The -repository's about page also lists the fingerprint (see the -\l{https://build2.org/pkg/hello/?about about page} for our repository). For -more details on repository signing see the \l{bpkg-repository-signing(1)} help -topic. +The \c{manifest} file is what makes a build system project a \i{package}. It +contains all the metadata that a user of a package might need to know: its +name, version, license, dependencies, etc., all in one place. -If we answer \i{yes}, we will see the basic repository information (its -\i{canonical name}, location, certificate subject and fingerprint) followed -by the list of available packages: +\N|Refer to \l{bpkg#manifest-format Manifest Format} for the general format of +\c{build2} manifest files and to \l{bpkg#manifest-package Package Manifest} +for details on the package manifest values.| -\ -build2.org/hello/stable https://build2.org/pkg/1/hello/stable -CN=build2.org/O=Code Synthesis/admin@build2.org -FF:DF:7D:38:67:4E:C3:82:[...]:30:56:B9:77:B9:F2:01:94 +As you can see, \c{manifest} created by \l{bdep-new(1)} contains some dummy +values which you would want to adjust before publishing your package. But +let's resist the urge to adjust that strange looking \c{0.1.0-a.0.z} until we +discuss package versioning. -hello/1.0.0 -libhello/1.0.0 -\ +\N|Next to \c{manifest} you might have noticed the \c{repositories.manifest} +file \- we will discuss its function later, when we talk about dependencies +and where they come from.| -We can also use the repository's web interface (implemented by \c{brep}). Our -repository has one, check it out: \c{\l{https://build2.org/pkg/hello/}}. +Project in hand, let's build it. Unlike other programming languages, C++ +development usually involves juggling a handful of build configurations: +several compilers and/or targets (\c{build2} is big on cross-compiling), +debug/release, different sanitizers and/or static analysis tools, and so +on. As a result, \c{build2} is optimized for multi-configuration +usage. However, as we will see shortly, one build configuration can be +designated as the default with additional conveniences. -Ok, back to the command line. If we want to use a repository as a source of -packages in our configuration, we have to first add it: +The \l{bdep-init(1)} command is used to initialize a project in a build +configuration. As a shortcut, it can also create a new build configuration in +the process, which is just what we need here. Let's start with GCC (remember +we are in the project's root directory): \ -$ bpkg add https://build2.org/pkg/1/hello/stable -added repository build2.org/hello/stable +$ bdep init -C ../hello-gcc @gcc cc config.cxx=g++ +initializing project /tmp/hello/ +created configuration @gcc /tmp/hello-gcc/ (default, auto-synchronized) +synchronizing: + new hello/0.1.0-a.0.19700101000000 \ -If we want to add several repositories, we just execute the \l{bpkg-rep-add(1) -\c{bpkg add}} command for each of them. Once this is done, we fetch the list of -available packages for all the added repositories: +The \cb{--create|-C} option instructs \c{init} to create a new configuration +in the specified directory (\c{../hello-gcc} in our case). To make referring +to configurations easier, we can give it a name, which is what we do with +\c{@gcc}. The next argument (\c{cc}, stands for \i{C-common}) is the build +system module we would like to configure. It implements compilation and +linking rules for the C and C++ languages. Finally, \c{config.cxx=g++} is (one +of) this module's configuration variables that specifies the C++ compiler we +would like to use (the corresponding C compiler will be determined +automatically). Let's for now also ignore that \c{synchronizing:...} bit along +with strange-looking \c{19700101000000} in the version \- it will become clear +what's going on here in a moment. + +Now the same for Clang: \ -$ bpkg fetch -fetching build2.org/hello/stable -2 package(s) in 1 repository(s) +$ bdep init -C ../hello-clang @clang cc config.cxx=clang++ +initializing project /tmp/hello/ +created configuration @clang /tmp/hello-clang/ (auto-synchronized) +synchronizing: + new hello/0.1.0-a.0.19700101000000 \ -Note that you would normally re-run the \l{bpkg-rep-fetch(1) \c{bpkg fetch}} -command after you've added another repository or to refresh the list of -available packages. - -Now that \c{bpkg} knows where to get the packages, we can finally get down to -business: +If we check the parent directory, we should now see two build configurations +next to our project: \ -$ bpkg build hello - build libhello/1.0.0 (required by hello) - build hello/1.0.0 -continue? [Y/n] +$ ls .. +hello/ +hello-gcc/ +hello-clang/ \ -Let's see what's going on here. We ran \l{bpkg-pkg-build(1) \c{bpkg build}} to -build the \c{hello} program which happens to depend on the \c{libhello} -library. So \c{bpkg} presents us with a \i{plan of action}, that is, the steps -it will have to perform in order to build us \c{hello} and then asks us to -confirm if that's what we want to do (you can add \c{--yes|-y} to skip the -confirmation). In the real-world usage the plan will be more complex, with -upgrades/downgrades, reconfigurations, etc. +Things will also look pretty similar if you are on Windows instead of a +UNIX-like operating system. For example, to initialize our project on Windows +with Visual Studio, start the Visual Studio development command prompt and +then run: -Let's answer \i{yes} and see what happens: +\N|Currently we have to run \c{build2} tools from a suitable Visual Studio +development command prompt. This requirement will likely be removed in the +future.| \ -libhello-1.0.0.tar.gz 100% of 2428 B 1364 kBps 00m01s -fetched libhello/1.0.0 -unpacked libhello/1.0.0 -hello-1.0.0.tar.gz 100% of 1057 B 20 MBps 00m01s -fetched hello/1.0.0 -unpacked hello/1.0.0 -configured libhello/1.0.0 -configured hello/1.0.0 -c++ hello-1.0.0/cxx{hello} -c++ libhello-1.0.0/hello/cxx{hello} -ld libhello-1.0.0/hello/libs{hello} -ld hello-1.0.0/exe{hello} -updated hello/1.0.0 +> bdep init -C ..\hello-debug @debug cc ^ + config.cxx=cl ^ + \"config.cc.coptions=/MDd /Z7\" ^ + config.cc.loptions=/DEBUG + +> bdep init -C ..\hello-release @release cc ^ + config.cxx=cl ^ + config.cc.coptions=/O2 \ -While the output is mostly self-explanatory, in short, \c{bpkg} downloaded, -unpacked, and configured both packages and then proceeded to building the -\c{hello} executable which happens to require building the \c{libhello} -library. Note that the download progress may look differently on your machine -depending on which \i{fetch tool} (\c{wget}, \c{curl}, or \c{fetch}) is -used. If you ever considered giving that \c{-v} option a try, now would be a -good time. But let's first drop (\l{bpkg-pkg-drop(1) \c{bpkg drop}}) the -\c{hello} package so that we get the same build from scratch: +\N|Besides the \c{coptions} (compile options) and \c{loptions} (link options), +other commonly used \c{cc} module configuration variables are \c{poptions} +(preprocess options) and \c{libs} (extra libraries to link). We can also use +their \c{config.c.*} (C compilation) and \c{config.cxx.*} (C++ compilation) +variants if we only want them applied during the respective language +compilation. For example: \ -$ bpkg drop hello -following prerequisite packages were automatically built and will no longer be necessary: - libhello -drop prerequisite packages? [Y/n] y - drop hello - drop libhello -continue? [Y/n] y -disfigured hello -disfigured libhello -purged hello -purged libhello +$ bdep init ... cc \ + config.cxx=clang++ \ + config.cc.coptions=-g \ + config.cxx.coptions=-stdlib=libc++ \ -Ok, ready for some \c{-v} details? Feel free to skip the following listing -if you are not interested. - -\ -$ bpkg build -v -y hello -fetching libhello-1.0.0.tar.gz from build2.org/hello/stable -curl ... https://build2.org/pkg/1/hello/stable/libhello-1.0.0.tar.gz - % Total % Received Average Speed Time Time Time Current - Dload Upload Total Spent Left Speed -100 2428 100 2428 1121 0 0:00:01 0:00:01 --:--:-- 1122 -fetched libhello/1.0.0 -tar -xf libhello-1.0.0.tar.gz -unpacked libhello/1.0.0 -fetching hello-1.0.0.tar.gz from build2.org/hello/stable -curl ... https://build2.org/pkg/1/hello/stable/hello-1.0.0.tar.gz - % Total % Received Average Speed Time Time Time Current - Dload Upload Total Spent Left Speed -100 1057 100 1057 773 0 0:00:01 0:00:01 --:--:-- 772 -fetched hello/1.0.0 -tar -xf hello-1.0.0.tar.gz -unpacked hello/1.0.0 -b -v configure(./libhello-1.0.0/) -cat >libhello-1.0.0/build/config.build -configured libhello/1.0.0 -b -v configure(./hello-1.0.0/) -cat >hello-1.0.0/build/config.build -configured hello/1.0.0 -hold package hello -b -v update(./hello-1.0.0/) -g++-5 -I libhello-1.0.0 -O3 -std=c++11 -o hello-1.0.0/hello.o -c hello-1.0.0/hello.cxx -g++-5 -I libhello-1.0.0 -O3 -std=c++11 -fPIC -o libhello-1.0.0/hello/hello.so.o -c libhello-1.0.0/hello/hello.cxx -g++-5 -O3 -std=c++11 -shared -o libhello-1.0.0/hello/libhello-1.0.so libhello-1.0.0/hello/hello.so.o -g++-5 -O3 -std=c++11 -o hello-1.0.0/hello hello-1.0.0/hello.o libhello-1.0.0/hello/libhello-1.0.so -updated hello/1.0.0 +| + +One difference you might have noticed when creating the \c{gcc} and \c{clang} +configurations above is that the first one was designated as the default. The +default configuration is used by \c{bdep} commands if no configuration is +specified explicitly (see \l{bdep-projects-configs(1)} for details). It is +also the configuration that is used if we run the build system in the +project's source directory. So, normally, you would make your every day +development configuration the default. Let's try that: + \ +$ bdep status +hello configured 0.1.0-a.0.19700101000000 + +$ b +c++ hello/cxx{hello}@../hello-gcc/hello/hello/ +ld ../hello-gcc/hello/hello/exe{hello} +ln ../hello-gcc/hello/hello/exe{hello} -> hello/ -Another handy command is \l{bpkg-pkg-status(1) \c{bpkg status}}. It can be -used to examine the state of a package in the configuration. Here are a few -examples (if you absolutely must know what \c{hold_package} and \c{sys:?} -mean, check \l{bpkg-pkg-status(1)}): +$ b test +test hello/test{testscript} ../hello-gcc/hello/hello/exe{hello} +$ hello/hello World +Hello, World! \ -$ bpkg status libhello -configured 1.0.0; available sys:? -$ bpkg status hello -configured 1.0.0 hold_package; available sys:? +In contrast, the Clang configuration has to be requested explicitly: -$ bpkg drop -y hello -disfigured hello -disfigured libhello -purged hello -purged libhello +\ +$ bdep status @clang +hello configured 0.1.0-a.0.19700101000000 + +$ b ../hello-clang/hello/ +c++ hello/cxx{hello}@../hello-clang/hello/hello/ +ld ../hello-clang/hello/hello/exe{hello} -$ bpkg status hello -available 1.0.0 sys:? +$ b test: ../hello-clang/hello/ +test hello/test{testscript} ../hello-clang/hello/hello/exe{hello} -$ bpkg status libfoobar -unknown +$ ../hello-clang/hello/hello/hello World +Hello, World! \ -Let's say we got wind of a new development: the \c{libhello} author released a -new version of the library. It is such an advance in the art of \i{\"Hello, -World!\"}, it's only currently available from \c{testing}. Of course, we must -check it out. +\N|To see the actual compilation command lines, run \c{b\ -v} and for even +more details, run \c{b\ -V}. See \l{b(1)} for more information on these +and other build system options.| -Now, what exactly is \c{testing}? You must have noticed that the repository -location that we've been using so far ended with \c{/stable}. Quite often it is -useful to split our repository into sub-repositories or \i{sections}. For -example, to reflect the maturity of packages (say, \c{stable} and \c{testing}, -as in our case) or to divide them into sub-categories (\c{misc} and \c{math}) -or even some combination (\c{math/testing}). Note, however, that to \c{bpkg} -these sub-repositories or \i{sections} are just normal repositories and there -is nothing special about them. +While we are here, let's also check how hard it would be to cross-compile: -We are impatient to try the new version so we will skip interrogating the -repository with \c{rep-info} and just add it to our configuration. After all, -we can always check with \c{status} if any upgrades are available for packages -we are interested in. Here we assume the configuration has \c{hello} built (run -\c{bpkg build -y hello} to get to that state). +\ +$ bdep init -C ../hello-mingw @mingw cc config.cxx=x86_64-w64-mingw32-g++ +initializing project /tmp/hello/ +created configuration @mingw /tmp/hello-mingw/ (auto-synchronized) +synchronizing: + new hello/0.1.0-a.0.19700101000000 +$ b ../hello-mingw/hello/ +c++ hello/cxx{hello}@../hello-mingw/hello/hello/ +ld ../hello-mingw/hello/hello/exe{hello} \ -$ bpkg add https://build2.org/pkg/1/hello/testing -added repository build2.org/hello/testing -$ bpkg fetch -fetching build2.org/hello/stable -fetching build2.org/hello/testing -5 package(s) in 2 repository(s) +As you can see, cross-compiling in \c{build2} is nothing special. In our case, +on a properly setup GNU/Linux machine (that automatically uses \c{wine} as an +\c{.exe} interpreter) we can even run tests (in \c{build2} this is called +\i{cross-testing}): + \ +$ b test: ../hello-mingw/hello/ +test hello/test{testscript} ../hello-mingw/hello/hello/exe{hello} -Notice that this time we don't see any authentication-related messages or -prompts since \c{bpkg} remembered (in this configuration) that we trust the -certificate (\c{testing} naturally uses the same one as \c{stable}). +$ ../hello-mingw/hello/hello/hello.exe Windows +Hello, Windows! +\ -Let's see what's new: +Let's review what it takes to initialize a project's infrastructure and +perform the first build. For an existing project: \ -$ bpkg status libhello -configured 1.0.0; available 1.1.0 sys:? +$ git clone .../hello.git +$ cd hello +$ bdep init -C ../hello-gcc @gcc cc config.cxx=g++ +$ b \ -Ok, \c{libhello/1.1.0} is now available. How do we upgrade? We can try to -build \c{hello} again: +For a new project: \ -$ bpkg build -y hello -info: dir{hello-1.0.0/} is up to date -updated hello/1.0.0 +$ bdep new -t exe -l c++ hello +$ cd hello +$ bdep init -C ../hello-gcc @gcc cc config.cxx=g++ +$ b \ -Why did nothing happen? Because \c{bpkg} will only upgrade (or downgrade) -to a new version if we explicitly ask it to. As things stand, all dependencies -for \c{hello} are satisfied and \c{bpkg} is happy to twiddle its thumbs. Let's -tell \c{bpkg} to build us \c{libhello} instead: +If you prefer, the \c{new} and \c{init} steps can be combined into a single +command: + +\ +$ bdep new -t exe -l c++ hello -C hello-gcc @gcc cc config.cxx=g++ +\ + +Now is also a good time to get an overview of the \c{build2} toolchain. After +all, we have already used two of its tools (\c{bdep} and \c{b}) without a +clear understanding of what they actually are. + +Unlike most other programming languages that encapsulate the build system, +package dependency manager, and project dependency manager into a single tool +(such as Rust's \c{cargo} or Go's \c{go}), \c{build2} is a hierarchy of +several tools that you will be using directly and which together with your +version control system (VCS) will constitute the core of your project +management toolset. + +\N|While \c{build2} can work without a VCS, this will result in reduced +functionality.| + +At the bottom of the hierarchy is the build system, \l{b(1)}. Next comes the +package dependency manager, \l{bpkg(1)}. It is primarily used for \i{package +consumption} and depends on the build system. The top of the hierarchy is the +project dependency manager, \l{bdep(1)}. It is used for \i{project +development} and relies on \c{bpkg} for building project packages and their +dependencies. + +\N|The main reason for this separation is modularity and the resulting +flexibility: there are situations where we only need the build system (for +example, when building a package for a system package manager where all the +dependencies should be satisfied from the system repository), or only the +build system and package manager (for example, when a build bot is building a +package for testing). + +Note also that strictly speaking \c{build2} is not C/C++-specific; its build +model is general enough to handle any DAG-based operations and its +package/project dependency management can be used for any compiled language.| + +\N|As we will see in a moment, \c{build2} also integrates with your VCS in +order to automate project versioning. Note that currently only \c{git(1)} is +supported.| + +Let's now move on to the reason why there is \i{dep} in the \c{bdep} name: +dependency management. + + +\h#guide-repositories|Package Repositories| + +Say we have realized that writing \i{\"Hello, World!\"} programs is a fairly +common task and that someone must have written a library to help with that. So +let's see if we can find something suitable to use in our project. + +Where should we look? That's a good question. But before we can try to answer +it, we need to understand where \c{build2} can source dependencies. In +\c{build2} packages come from \i{package repositories}. Two commonly used +repository types are \i{version control} and \i{archive}-based (see +\l{bpkg-repository-types(1)} for details). + +As the name suggests, a version control-based repository uses a VCS as its +distribution mechanism. \N{Currently, only \c{git} is supported.} Such a +repository normally contains multiple versions of a single package or, +perhaps, of a few related packages. + +An archive-based repository contains multiple, potentially unrelated +packages/versions as archives along with some meta information (package list, +prerequisite/complement repositories, signatures, etc) that are all accessible +via HTTP(S). + +Version control and archive-based repositories have different +trade-offs. Version control-based repositories are great for package +developers: With services like GitHub they are trivial to setup. In fact, your +project's (already existing) VCS repository will normally be the \c{build2} +package repository \- you might need to add a few files, but that's about it. + +However, version control-based repositories are not without drawbacks: It will +be hard for your users to discover your packages (try searching for \"hello +library\" on GitHub \- most of the results are not even in C++ let alone +packaged for \c{build2}). There is also the issue of continuous availability: +users can delete their repositories, services may change their policies or go +out of business, and so on. Version control-based repositories also lack +repository authentication and package signing. Finally, obtaining the +available package list for such repositories can be slow. + +A central, archive-based repository would address all these drawbacks: It +would be a single place to search for packages. Published packages will never +disappear and can be easily mirrored. Packages are signed and the repository +is authenticated (see \l{bpkg-repository-signing(1)} for details). And, last, +but not least, archive-based repositories are fast. + +\l{https://cppget.org cppget.org} is the \c{build2} community's central +package repository (which we hope one day will become \i{the C++ package +repository}). As an added benefit, packages on \l{https://cppget.org +cppget.org} are continuously \l{https://cppget.org/?builds built and tested} on +all the major platform/compiler combinations with the results available as +part of the package description. + +\N|The main drawback of archive-based repositories is the setup cost. Getting +a basic repository going is relatively easy \- all you need is an HTTP(S) +server. Adding a repository web interface like that on \l{https://cppget.org +cppget.org} will require running \l{https://cppget.org/brep \c{brep}}. And +adding CI will require running a bunch of build bots +(\l{https://cppget.org/bbot \c{bbot}}).| + +\N|CI support for version control-based repositories is a work in progress.| + +To summarize, version control-based repositories are great for package +developers while a central, archive-based repository is convenient for package +consumers. A reasonable strategy is then for package developers to publish +their releases to a central repository. Package consumers can then decide +which repository to use based on their needs. For example, one could use +\l{https://cppget.org cppget.org} as a (fast, reliable, and secure) source of +stable versions but also add, say, \c{git} repositories for select packages +(perhaps with the \c{#HEAD} fragment filter to improve download speed) for +testing development snapshots. In this model the two repository types +complement each other. + +\N|Support for automated publishing of tagged releases to an archive-based +repository is a work in progress.| + +Let's see how all this works in practice. Go over to \l{https://cppget.org +cppget.org} and type \"hello library\" in the search box. At the top of the +search result you should see the \l{https://cppget.org/libhello \c{libhello}} +package and if you follow the link you will see the package description page +along with a list of available versions. Pick a version that you like and you +will see the package version description page with quite a bit of information, +including the list of platform/compiler combinations that this version has +been successfully (or unsuccessfully) tested with. If you like what you see, +copy the \c{location} value \- this is the repository location where this +package version can be sourced from. + +\N|The \l{https://cppget.org cppget.org} repository is split into several +sections: \c{stable}, \c{testing}, \c{beta}, \c{alpha} and \c{legacy}, with +each section having its own repository location (see the repository's +\l{https://cppget.org/?about about} page for details on each section's +policies). Note also that \c{testing} is complemented by \c{stable}, \c{beta} +by \c{testing}, and so on, so you only need to choose the lowest stability +level and you will automatically \"see\" packages from the more stable +sections.| + +\N|The \l{https://cppget.org cppget.org} \c{stable} sections will always +contain the \c{libhello} library version \c{1.0.X} that was generated using +the following \l{bdep-new(1)} command line: + +\ +$ bdep new -t lib -l c++ libhello +\ + +It can be used as a predictable test dependency when setting up new projects.| + +Let's say we've visited the \c{libhello} project's +\l{https://git.build2.org/cgit/hello/libhello/ home page} (for example by +following a link from the package details page) and noticed that it is being +developed in a \c{git} repository. How can we see what's available there? If +the releases are tagged, then we can infer the available released versions +from the tags. But that doesn't tell us anything about what's happening on the +\c{HEAD} or in the branches. For that we can use the package manager's +\l{bpkg-rep-info(1)} command: + +\ +$ bpkg rep-info https://git.build2.org/hello/libhello.git +libhello/1.0.0 +libhello/1.1.0 +\ + +As you can see, besides \c{1.0.0} that we have seen on \c{cppget.org/stable}, +there is also \c{1.1.0} (which is perhaps being tested in +\c{cppget.org/testing}). We can also check what might be available on the +\c{HEAD} (see \l{bpkg-repository-types(1)} for details on the \c{git} +repository URL format): \ -$ bpkg build libhello - build libformat/1.0.0 (required by libhello) - build libprint/1.0.0 (required by libhello) - upgrade libhello/1.1.0 - reconfigure hello (dependent of libhello) -continue? [Y/n] +$ bpkg rep-info https://git.build2.org/hello/libhello.git#HEAD +libhello/1.1.1-a.0.20180504111511.2e82f7378519 \ -Ok, now we are getting somewhere. It looks like the new version of \c{libhello} -went really enterprise-grade (or is it called web-scale these days?). There are -now two new dependencies (\c{libformat} and \c{libprint}) that we will have to -build in order to upgrade. Maybe we should answer \i{no} here? +\N|We can also use the \c{rep-info} command on archive-based repositories, +however, if available, the web interface is usually more convenient and +provides more information.| -Notice also that \c{reconfigure hello} line. If you think about this, it makes -sense: we are getting a new version of \c{libhello} and \c{hello} depends on it -so it might need a chance to make some adjustments to its configuration. +To summarize, we found two repositories for the \c{libhello} package: the +archive-based \l{https://cppget.org cppget.org} that contains the released +versions as well as its development \c{git} repository where we can get the +bleeding edge stuff. Let's now see how we can add \c{libhello} to our +project. -Let's answer \i{yes} if only to see what happens: + +\h#guide-add-remove-deps|Adding and Removing Dependencies| + +So we found \c{libhello} that we would like to use in our \c{hello} +project. First, we edit the \c{repositories.manifest} file found in the root +directory of our project and add one of the \c{libhello} repositories as a +prerequisite. Let's start with \l{https://cppget.org cppget.org}: \ -update dependent packages? [Y/n] +role: prerequisite +location: https://pkg.cppget.org/1/stable \ -Another question. This one has to do with that \c{reconfigure hello} line we -just talked about. If you were wondering why we were only offered to -reconfigure and not actually update the dependent package, you should know -that \c{bpkg} is a very lazy package manager, it only does what it must do, -not what might be nice to do. It must reconfigure but it doesn't really have -to update. And this could be a good thing if, for example, you have a hundred -dependents in your configuration but right now you only want to build just -those specific packages. However, quite often, you do want to keep all the -packages in your configuration up to date and \c{bpkg} graciously offers to -take care of this task. Ok, let's answer \i{yes} again: +\N|Refer to \l{bpkg#manifest-repository Repository Manifest} for details on +the repository manifest values.| + +Next, we edit the \c{manifest} file (again, found in the root of our project) +and specify the dependency on \c{libhello} with optional version constraint. +For example: \ -... -update dependent packages? [Y/n] y -disfigured hello/1.0.0 -disfigured libhello/1.0.0 -libformat-1.0.0.tar.gz 100% of 1064 B 11 MBps 00m01s -fetched libformat/1.0.0 -unpacked libformat/1.0.0 -libprint-1.0.0.tar.gz 100% of 1040 B 9 MBps 00m01s -fetched libprint/1.0.0 -unpacked libprint/1.0.0 -libhello-1.1.0.tar.gz 100% of 1564 B 4672 kBps 00m01s -fetched libhello/1.1.0 -unpacked libhello/1.1.0 -configured libformat/1.0.0 -configured libprint/1.0.0 -configured libhello/1.1.0 -configured hello/1.0.0 -c++ libhello-1.1.0/hello/cxx{hello} -c++ libformat-1.0.0/format/cxx{format} -ld libformat-1.0.0/format/liba{format} -c++ libprint-1.0.0/print/cxx{print} -ld libprint-1.0.0/print/liba{print} -ld libhello-1.1.0/hello/liba{hello} -c++ libhello-1.1.0/hello/cxx{hello} -c++ libformat-1.0.0/format/cxx{format} -ld libformat-1.0.0/format/libs{format} -c++ libprint-1.0.0/print/cxx{print} -ld libprint-1.0.0/print/libs{print} -ld libhello-1.1.0/hello/libs{hello} -c++ libhello-1.1.0/tests/test/cxx{driver} -ld libhello-1.1.0/tests/test/exe{driver} -c++ hello-1.0.0/cxx{hello} -ld hello-1.0.0/exe{hello} -updated libhello/1.1.0 -updated hello/1.0.0 +depends: libhello ^1.0.0 \ -A lot of output but nothing really new. If you were to answer \i{no} to the -\"update dependent packages?\" question above, it is easy to make sure a -package is up-to-date at a later time with the \l{bpkg-pkg-update(1) \c{bpkg -update}} command (there is also \l{bpkg-pkg-clean(1) \c{bpkg clean}}), for -example: +Let's briefly discuss version constraints (for details see the +\l{bpkg#manifest-package-depends \c{depends}} value documentation). A version +constraint can be expressed with a comparison operator (\c{==}, \c{>}, +\c{<}, \c{>=}, \c{<=}), a range shortcut operator (\c{~} and \c{^}), or a +range. Here are a few examples: \ -$ bpkg clean hello -rm hello-1.0.0/exe{hello} -rm hello-1.0.0/obje{hello} -cleaned hello/1.0.0 +depends: libhello == 1.2.3 +depends: libhello >= 1.2.3 -$ bpkg update hello -c++ hello-1.0.0/cxx{hello.cxx} -ld hello-1.0.0/exe{hello} -updated hello/1.0.0 +depends: libhello ~1.2.3 +depends: libhello ^1.2.3 + +depends: libhello [1.2.3 1.2.9) \ -Let's say we really don't like the direction \c{libhello} is going and would -rather stick to version \c{1.0.0}. Just like upgrades, downgrades are explicit -plus, in this case, we need to specify the version (you can also specify -the desired version for upgrades). +You may already be familiar with the tilde (\c{~}) and caret (\c{^}) +constraints from dependency managers for other languages. To recap, tilde +allows upgrades to any further patch versions while caret also allows upgrades +to further minor versions. They are equivalent to the following ranges: \ -$ bpkg build libhello/1.0.0 - downgrade libhello/1.0.0 - reconfigure hello (dependent of libhello) -continue? [Y/n] y -update dependent packages? [Y/n] y -disfigured hello/1.0.0 -disfigured libhello/1.1.0 -libhello-1.0.0.tar.gz 100% of 2428 B 983 kBps 00m01s -fetched libhello/1.0.0 -unpacked libhello/1.0.0 -configured libhello/1.0.0 -configured hello/1.0.0 -following prerequisite packages were automatically built and will no longer be necessary: - libprint - libformat -drop prerequisite packages? [Y/n] y -disfigured libprint -disfigured libformat -purged libprint -purged libformat -c++ libhello-1.0.0/hello/cxx{hello} -ld libhello-1.0.0/hello/liba{hello} -c++ libhello-1.0.0/hello/cxx{hello} -ld libhello-1.0.0/hello/libs{hello} -c++ libhello-1.0.0/tests/test/cxx{driver} -ld libhello-1.0.0/tests/test/exe{driver} -c++ hello-1.0.0/cxx{hello} -ld hello-1.0.0/exe{hello} -updated libhello/1.0.0 -updated hello/1.0.0 +~X.Y.Z [X.Y.Z X.Y+1.0) + +^X.Y.Z [X.Y.Z X+1.0.0) if X > 0 +^0.Y.Z [0.Y.Z 0.Y+1.0) if X == 0 \ -Notice how \c{bpkg} helpfully offered to get rid of \c{libprint} and -\c{libformat} which we won't be needing anymore. Note also that while we -can use \c{--yes|y} as an answer to all the numerous prompts, there are -also more granular options. For example, this is how we can instruct -\c{bpkg} to drop prerequisites (\c{--drop-prerequisite|-D}) but leave -dependents just reconfigured (\c{--leave-dependent|-L}): +\N|Zero major version component is customarily used during early development +where the minor version effectively becomes major. As a result, the tilde +constraint has a special treatment of this case.| + +Unless you have good reasons not to (for example, a dependency does not use +semantic versioning), we suggest that you use the \c{^} constraint which +provides a good balance between compatibility and upgradability with \c{~} +being a more conservative option. + +Ok, we've specified where our package comes from (\c{repositories.manifest}) +and which versions we find acceptable (\c{manifest}). The next step is to edit +\c{hello/buildfile} and import the \c{libhello} library into our build: \ -$ bpkg build -D -L libhello/1.0.0 +import libs += libhello%lib{hello} \ -Ok, so all this might look nice and all, but we haven't actually seen anything -of what we've presumably built; it can all be a charade, for all we know. Can -we see some libraries and run the \c{hello} program? +Finally, we modify our source code to use the library: -There are several ways we can do this. If the package provides tests (as all -good packages should), we can run them with the \l{bpkg-pkg-test(1) \c{bpkg -test}} command: +\ +#include +... + +int main (int argc, char* argv[]) +{ + ... + hello::say_hello (cout, argv[1]); +} +\ + +\N|You are probably wondering why we have to specify this repeating +information in so many places. Let's start with the source code: we can't +specify the version constraint or location there because it will have to be +repeated in every source file that uses the dependency. + +Moving up, \c{buildfile} is also not a good place to specify this information +for the same reason (a library can be imported in multiple buildfiles) plus +the build system doesn't really know anything about version constraints or +repositories which is the purview of the dependency management tools. + +Finally, we have to separate the version constraint and the location because +the same package can be present in multiple repositories with different +policies. For example, when a package from a version control-based repository +is published in an archive-based repository, its \c{repositories.manifest} +file is ignored and all its dependencies should be available from the +archive-based repository itself (or its fixed set of prerequisite +repositories). In other words, \c{manifest} belongs to a package while +\c{repositories.manifest} \- to a repository. + +Also note that this is unlikely to become burdensome since adding new +dependencies is not something that happens often. There are also plans to +automate this with a \c{bdep-add(1)} command in the future.| + +To summarize, these are the files we had to modify to add a dependency +to our project: \ -$ bpkg test libhello hello -test libhello-1.0.0/tests/test/exe{driver} -test hello-1.0.0/exe{hello} -tested libhello/1.0.0 -tested hello/1.0.0 +repositories.manifest # add https://pkg.cppget.org/1/stable +manifest # add 'depends: libhello ^1.0.0' +buildfile # import libhello +hello.cxx # use libhello \ -But that doesn't quite count for seeing libraries and running programs. Well, -if you insist, let's see what's inside \c{hello-gcc5-release/}. The \c{bpkg} -configuration (this \c{hello-gcc5-release/} directory) is, in the \c{build2} -build system terms, an \i{amalgamation} \- a project that contains -\i{subprojects}. Not surprisingly, the subprojects in this amalgamation are the -packages that we've built: +With a new dependency added, let's check the status of our project: \ -$ ls -1F -build/ -hello-1.0.0/ -libhello-1.0.0/ -buildfile -hello-1.0.0.tar.gz -libhello-1.0.0.tar.gz +$ bdep status +fetching pkg:cppget.org/stable (prerequisite of dir:/tmp/hello) +warning: authenticity of the certificate for pkg:cppget.org/stable + cannot be established +certificate is for cppget.org, \"Code Synthesis\" +certificate SHA256 fingerprint: +86:BA:D4:DE:2C:87:1A:EE:38:<...>:5A:EA:F4:F7:8C:1D:63:30:C6 +trust this certificate? [y/n] y + +hello configured 0.1.0-a.0.19700101000000 + available 0.1.0-a.0.19700101000000#1 \ -And if we look inside \c{hello-1.0.0/} we will see what looks like the -\c{hello} program: +The \l{bdep-status(1)} command has detected that the dependency information +has changed and tells us that a new \i{iteration} of our project (that \c{#1}) +is now available for \i{synchronization} with the build configuration. + +We've also been prompted to authenticate the prerequisite repository. This +will have to happen once for every build configuration we initialize our +project in and can quickly become tedious. To overcome this, we can mention +the certificate fingerprint that we wish to automatically trust in the +\c{repositories.manifest} file (replace it with the actual fingerprint from +the repository's about page): \ -$ ls -1F hello-1.0.0/ -build/ -buildfile -hello* -hello.d -hello.cxx -hello.o -hello.o.d -manifest -test.out -version +role: prerequisite +location: https://pkg.cppget.org/1/stable +trust: 86:BA:D4:DE:2C:87:1A:EE:38:<...>:5A:EA:F4:F7:8C:1D:63:30:C6 +\ -$ hello-1.0.0/hello -usage: hello ... +To synchronize a project with one or more build configurations we use the +\l{bdep-sync(1)} command: -$ hello-1.0.0/hello World -Hello, World! +\ +$ bdep sync +synchronizing: + new libhello/1.0.0 (required by hello) + upgrade hello/0.1.0-a.0.19700101000000#1 \ -The important point here is this: the \c{bpkg} configuration is not some black -box that you should never look inside of. On the contrary, it is a normal and -predictable concept of the build system and as long as you understand what you -are doing, feel free to muck around. - -Another way to get hold of a package's goodies is to install it with -\l{bpkg-pkg-install(1) \c{bpkg install}}. Let's try that: - -\ -$ bpkg install \ - config.install.root=/opt/hello \ - config.install.sudo=sudo \ - hello - -install /opt/hello/ -install /opt/hello/include/ -install /opt/hello/include/hello/ -install libhello-1.0.0/hello/hxx{hello} -install libhello-1.0.0/hello/hxx{export} -install /opt/hello/lib/ -install libhello-1.0.0/hello/libs{hello} -install /opt/hello/bin/ -install hello-1.0.0/exe{hello} -install /opt/hello/share/ -install /opt/hello/share/doc/ -install /opt/hello/share/doc/hello/ -install hello-1.0.0/doc{version} -installed hello/1.0.0 -\ - -The \c{config.install.sudo} value is the optional \i{sudo}-like program -that should be used to run the \c{install} program. For those feeling queasy -running \c{sudo make install}, here is your answer. If you are wondering -whether you could have specified those \c{config.install.*} values during the -configuration creation, the answer is yes, indeed! - -Let's see what we've got: - -\ -$ tree -F /opt/hello/ -/opt/hello/ -├── bin/ -│ └── hello* -├── include/ -│ └── libhello/ -│ ├── export -│ └── hello -├── lib/ -│ ├── libhello-1.0.so* -│ └── libhello.so -> libhello-1.0.so* -└── share/ - └── doc/ - └── hello/ - └── version -\ - -We can also try to run the installed program: - -\ -$ /opt/hello/bin/hello World -/opt/hello/bin/hello: error while loading shared libraries: libhello-1.0.so: cannot open shared object file: No such file or directory -\ - -Not what we hoped to see. Note to the Windows users: this will actually work -since \c{hello-1.0.dll} will be installed into \c{bin\\}, next to the -executable; for once things are working better on Windows. - -The problem is with our installation location: the runtime linker won't look -for \c{libhello-1.0.so} in \c{/opt/hello/lib} unless we somehow tell it to -(for example, using \c{LD_LIBRARY_PATH} or equivalent). There are several -ways we can resolve this. We could give up on shared libraries and link our -prerequisite libraries statically (\c{config.bin.exe.lib=static}). Or we could -use the \i{rpath} mechanism: - -\ -$ bpkg install \ - config.install.root=/opt/hello \ - config.install.sudo=sudo \ - config.bin.rpath=/opt/hello/lib \ - hello - -ld hello-1.0.0/exe{hello} -install /opt/hello/ -install /opt/hello/include/ -install /opt/hello/include/hello/ -install libhello-1.0.0/hello/hxx{hello} -install libhello-1.0.0/hello/hxx{export} -install /opt/hello/lib/ -install libhello-1.0.0/hello/libs{hello} -install /opt/hello/bin/ -install hello-1.0.0/exe{hello} -install /opt/hello/share/ -install /opt/hello/share/doc/ -install /opt/hello/share/doc/hello/ -install hello-1.0.0/doc{version} -installed hello/1.0.0 - -$ /opt/hello/bin/hello World -Hello, World! +Or we could just build the project without an explicit \c{sync} \- if +necessary, it will be automatically synchronized: + +\ +$ b +synchronizing: + new libhello/1.0.0 (required by hello) + upgrade hello/0.1.0-a.0.19700101000000#1 +c++ ../hello-gcc/libhello-1.0.0/libhello/cxx{hello} +ld ../hello-gcc/libhello-1.0.0/libhello/libs{hello} +c++ hello/cxx{hello}@../hello-gcc/hello/hello/ +ld ../hello-gcc/hello/hello/exe{hello} +ln ../hello-gcc/hello/hello/exe{hello} -> hello/ \ -Notice that \c{ld} line above \- this is where our executable is re-linked -with the \c{-rpath} option. +The synchronization as performed by the \c{sync} command is two-way: +dependency packages are first added, removed, upgraded, or downgraded in build +configurations according to the project's version constraints and user +input. Then the actual versions of the dependencies present in the build +configurations are recorded in the project's \c{lockfile} so that if desired, +the build can be reproduced exactly. \N{The \c{lockfile} functionality is not +yet implemented.} For a new dependency the latest available version that +satisfies the version constraint is used. + +\N|Synchronization is also the last step in the \l{bdep-init(1)} command's +logic.| -We can also uninstall what we have installed with \l{bpkg-pkg-uninstall(1) -\c{bpkg uninstall}}: +Let's now examine the status in all (\c{--all|-a}) the build configurations +and include the immediate dependencies (\c{--immediate|-i}): \ -$ bpkg uninstall \ - config.install.root=/opt/hello \ - config.install.sudo=sudo \ - hello +$ bdep status -ai +in configuration @gcc: +hello configured 0.1.0-a.0.19700101000000#1 + libhello ^1.0.0 configured 1.0.0 -uninstall hello-1.0.0/doc{version} -uninstall /opt/hello/share/doc/hello/ -uninstall /opt/hello/share/doc/ -uninstall /opt/hello/share/ -uninstall hello-1.0.0/exe{hello} -uninstall /opt/hello/bin/ -uninstall libhello-1.0.0/hello/libs{hello} -uninstall /opt/hello/lib/ -uninstall libhello-1.0.0/hello/hxx{export} -uninstall libhello-1.0.0/hello/hxx{hello} -uninstall /opt/hello/include/hello/ -uninstall /opt/hello/include/ -uninstall /opt/hello/ -uninstalled hello/1.0.0 +in configuration @clang: +hello configured 0.1.0-a.0.19700101000000 + available 0.1.0-a.0.19700101000000#1 +\ + +Since we didn't specify a configuration explicitly, only the default (\c{gcc}) +was synchronized. Normally, you would try a new dependency in one +configuration, make sure everything looks good, then synchronize the rest with +\c{--all|-a} (or, again, just build what you need directly). Here are a few +examples (see \l{bdep-projects-configs(1)} for details): -$ ls /opt/hello -ls: cannot access /opt/hello: No such file or directory +\ +$ bdep sync -a +$ bdep sync @gcc @clang +$ bdep sync -c ../hello-mingw \ -What if we wanted to use \c{libhello} in our own project? While installing it -is always an option, this may not be convenient when we develop our code. We -may have multiple builds per project, for example, with GCC and Clang to catch -all the warnings. We may also want to make sure our application works well -with several versions of \c{libhello} (and maybe even with that heinous -\c{1.1.X}). While we can install different configurations into different -directories, it's hard to deny things are getting a bit hairy: multiple -configurations, multiple installations... I guess we will have to get our -hands into that cookie jar, I mean, configuration, again. +To get rid of a dependency, we simply remove it from the \c{manifest} file +and synchronize the project. For example, assuming \c{libhello} is no longer +mentioned as a dependency in our \c{manifests}: -In fact, let's just start writing our own version of the \c{hello} program -and see how it goes: +\ +$ bdep status +hello configured 0.1.0-a.0.19700101000000#1 + available 0.1.0-a.0.19700101000000#2 +$ bdep sync +synchronizing: + drop libhello/1.0.0 (unused) + upgrade hello/0.1.0-a.0.19700101000000#2 \ -$ mkdir hello2 -$ cd hello2 -$ cat >hello.cpp -#include +\h#guide-upgrade-downgrade-deps|Upgrading and Downgrading Dependencies| -int main () -{ - hello::say (\"World\"); -} +Let's say we would like to try that \c{1.1.0} version we have seen in +the \c{libhello} \c{git} repository. First, we need to add the +repository to the \c{repositories.manifest} file: \ +role: prerequisite +location: https://git.build2.org/hello/libhello.git +\ -What build system shall we use? I can't believe you are even asking this -question... +\N|Note that we don't need the \c{trust} value since \c{git} repositories +are not authenticated.| -\ -$ mkdir build +To refresh the list of available dependency versions we use the +\l{bdep-fetch(1)} command (or the \c{--fetch|-f} option to \c{status}): -$ cat >build/bootstrap.build +\ +$ bdep fetch +$ bdep status libhello +libhello configured 1.0.0 available [1.1.0] +\ -project = hello2 # project name -using config # config module (those config.*) +To upgrade (or downgrade) dependencies we again use the \l{bdep-sync(1)} +command. We can upgrade one or more specific dependencies by listing them +as arguments to \c{sync}: -$ cat >build/root.build +\ +$ bdep sync libhello +synchronizing: + new libformat/1.0.0 (required by libhello) + new libprint/1.0.0 (required by libhello) + upgrade libhello/1.1.0 + upgrade hello/0.1.0-a.0.19700101000000#3 +\ -cxx.std = 11 # C++ standard -using cxx # C++ module -cxx{*}: extension = cpp # C++ source file extension +Without an explicit version or the \c{--patch|-p} option, \c{sync} will +upgrade the specified dependencies to the latest available versions. For +example, if we don't like version \c{1.1.0}, we can downgrade it back to +\c{1.0.0} by specifying the version explicitly (we pass \c{--old-available|-o} +to \c{status} to see the old versions): -$ cat >buildfile +\ +$ bdep status -o libhello +libhello configured 1.1.0 available (1.1.0) [1.0.0] -import libs = libhello%lib{hello} -exe{hello}: cxx{hello} $libs +$ bdep sync libhello/1.0.0 +synchronizing: + drop libprint/1.0.0 (unused) + drop libformat/1.0.0 (unused) + downgrade libhello/1.0.0 + reconfigure hello/0.1.0-a.0.19700101000000#3 \ -While some of this might not be crystal clear (like why do we have -\c{bootstrap.build} \i{and} \c{root.build}), I am sure you at least have a -fuzzy idea of what's going on. And that's enough for what we are after here. -Completely explaining what's going on here and, more importantly, \i{why} it's -going this way is for another time and place (the \c{build2} build system -manual). +\N|The available versions are listed in the descending order with \c{[]} +indicating that the version is only available as a dependency and \c{()} +marking the current version.| -To recap, these are the contents of our project so far: +Instead of specific dependencies we can also upgrade (\c{--upgrade|-u}) or +patch (\c{--patch|-p}) immediate (\c{--immediate|-i}) or all +(\c{--recursive|-r}) dependencies of our project. + +As a more realistic example, version \c{1.1.0} of \c{libhello} depends on two +other libraries: \c{libformat} and \c{libprint}. Here is our project's +dependency tree while we were still using that version: \ -$ tree -F -. -├── build/ -│ ├── bootstrap.build -│ └── root.build -├── buildfile -└── hello.cpp +$ bdep status -r +hello configured 0.1.0-a.0.19700101000000#3 + libhello ^1.0.0 configured 1.1.0 + libformat ^1.0.0 configured 1.0.0 + libprint ^1.0.0 configured 1.0.0 \ -Let's try to build it and see what happens \- maybe it will magically work -(\l{b(1)} is the \c{build2} build system driver). +A typical conservative dependency management workflow would look like this: \ -$ b config.cxx=g++-5 -error: unable to import target libhello%lib{hello} - info: use config.import.libhello command line variable to specifying its project out_root - info: while applying rule cxx.link to update exe{hello} - info: while applying rule alias to update dir{./} +$ bdep status -fi # refresh and examine immediate dependencies +hello configured 0.1.0-a.0.19700101000000#3 + libhello configured 1.1.0 available [2.0.0] [1.2.0] [1.1.2] [1.1.1] + +$ bdep sync -pi # upgrade immediate to latest patch version +synchronizing: + upgrade libhello/1.1.2 + reconfigure hello/0.1.0-a.0.19700101000000#3 +continue? [Y/n] y \ -No magic, unfortunately (or fortunately). But we got a hint: looks like we -need to tell \c{build2} where \c{libhello} is using -\c{config.import.libhello}. Without fretting too much about what exactly -\c{out_root} means, let's point \c{build2} to our \c{bpkg} configuration and -see what happens. After all, that's where, more or less, our \i{out}-put for -\c{libhello} is. +Notice that in case of such mass upgrades you are prompted for confirmation +before anything is actually changed (unless you pass \c{--yes|-y}). + +In contrast, the following would be a fairly aggressive workflow where we +upgrade everything to the latest available version (version constraints +permitting; here we assume \c{^1.0.0} was used for all the dependencies): \ -$ b config.cxx=g++-5 \ - config.import.libhello=/tmp/hello-gcc5-release -c++ cxx{hello} -ld exe{hello} +$ bdep status -fr # refresh and examine all dependencies +hello configured 0.1.0-a.0.19700101000000#3 + libhello configured 1.1.0 available [2.0.0] [1.2.0] [1.1.1] + libprint configured 1.0.0 available [2.0.0] [1.1.0] [1.0.1] + libformat configured 1.0.0 available [2.0.0] [1.1.0] [1.0.1] + +$ bdep sync -ur # upgrade all to latest available version +synchronizing: + upgrade libprint/1.1.0 + upgrade libformat/1.1.0 + upgrade libhello/1.2.0 + reconfigure hello/0.1.0-a.0.19700101000000#3 +continue? [Y/n] y \ -Almost magic. Let's see what we've got: +We can also have something in between: patch all (\c{sync\ -pr}), upgrade +immediate (\c{sync\ -ui}), or even upgrade immediate and patch the rest +(\c{sync\ -ui} followed by \c{sync\ -pr}). -\ -$ tree -F -. -├── build/ -│ ├── bootstrap.build -│ └── root.build -├── buildfile -├── hello* -├── hello.d -├── hello.cpp -├── hello.o -└── hello.o.d -$ ./hello -Hello, World! -\ +\h#guide-versioning-releasing|Versioning and Release Management| + +Let's now discuss versioning and release management and, yes, that +strange-looking \c{0.1.0-a.0.19700101000000} we keep seeing. While a build +system project doesn't need a version and a \c{bpkg} package can use custom +versioning schemes (see \l{bpkg#package-version Package Version}), a project +managed by \c{bdep} must use \i{standard versioning}. \N{A dependency, which +is a \c{bpkg} package, need not use standard versioning.} + +Standard versioning (\i{stdver}) is a \l{https://semver.org semantic +versioning} (\i{semver}) scheme with a more precisely defined pre-release +component and without any build metadata. + +\N|If you believe that \i{semver} is just \c{\i{major}.\i{minor}.\i{patch}}, +then in your worldview \i{stdver} would be the same as \i{semver}. In reality, +\i{semver} also allows loosely defined pre-release and build metadata +components. For example, \c{1.2.3-beta.1+build.23456} is a valid \i{semver}.| + +A standard version has the following form: + +\c{\i{major}\b{.}\i{minor}\b{.}\i{patch}[\b{-}\i{prerel}]} + +The \ci{major}, \ci{minor}, and \ci{patch} components have the same meaning as +in \i{semver}. The \ci{prerel} component is used to provide \i{continuous +versioning} of our project between releases. Specifically, during development +of a new version we may want to publish several pre-releases, for example, +alpha or beta. In between those we may also want to publish a number of +snapshots, for example, for CI. With continuous versioning all these releases, +pre-releases, and snapshots are assigned unique, properly ordered versions. + +\N|Continuous versioning is a cornerstone of the \c{build2} project dependency +management. In case of snapshots, an appropriate version is assigned +automatically in cooperation with your VCS.| + +The \ci{prerel} component for a pre-release has the following form: + +\c{(\b{a}|\b{b})\b{.}\i{num}} -Let's change something in our source code and try to update: +Here \cb{a} stands for alpha, \cb{b} stands for beta, and \ci{num} is the +alpha/beta number. For example: \ -$ touch hello.cpp +1.1.0 # final release for 1.1.0 +1.2.0-a.1 # first alpha pre-release for 1.2.0 +1.2.0-a.2 # second alpha pre-release for 1.2.0 +1.2.0-b.1 # first beta pre-release for 1.2.0 +1.2.0 # final release for 1.2.0 +\ -$ b -error: unable to import target libhello%lib{hello} - info: use config.import.libhello command line variable to specifying its project out_root - info: while applying rule cxx.link to update exe{hello} - info: while applying rule alias to update dir{./} +The \ci{prerel} component for a snapshot has the following form: + +\c{(\b{a}|\b{b})\b{.}\i{num}\b{.}\i{snapsn}[\b{.}\i{snapid}]} + +Where \ci{snapsn} is the snapshot sequence number and \ci{snapid} is +the snapshot id. In case of \c{git}, \ci{snapsn} is the commit timestamp +in the \c{YYYYMMDDhhmmss} form and UTC timezone while \ci{snapid} is +a 12-character abbreviated commit id. For example: + +\ +1.2.3-a.1.20180319215815.26efe301f4a7 \ -Looks like we have to keep repeating those \c{config.*} values and who wants -that? To get rid of this annoyance we have to make our configuration -\i{permanent}. Also, seeing that we plan to have several of them (GCC/Clang, -different version of \c{libhello}), it makes sense to create them \i{out of -source tree}. Let's get to it: +Notice also that a snapshot version is ordered \i{after} the corresponding +pre-release version. That is, \c{1.2.3-a.1\ <\ 1.2.3-a.1.1}. As a result, it +is customary to start the development of a new version with \c{X.Y.Z-a.0.z}, +that is, a snapshot after the (non-existent) zero'th alpha release. \N{We will +explain the meaning of \cb{z} in this version momentarily.} The following +chronologically-ordered versions illustrate a typical release flow of a +project that uses \c{git} as its VCS: \ -$ cd .. -$ mkdir hello2-gcc5-release -$ ls -1F -hello2/ -hello2-gcc5-release/ +0.1.0-a.0.19700101000000 # snapshot (no commits yet) +0.1.0-a.0.20180319215815.26efe301f4a7 # snapshot (first commit) +... # more commits/snapshots +0.1.0-a.1 # pre-release (first alpha) +0.1.0-a.1.20180319221826.a6f0f41205b8 # snapshot +... # more commits/snapshots +0.1.0-a.2 # pre-release (second alpha) +0.1.0-a.2.20180319231937.b701052316c9 # snapshot +... # more commits/snapshots +0.1.0-b.1 # pre-release (first beta) +0.1.0-b.1.20180319242038.c812163417da # snapshot +... # more commits/snapshots +0.1.0 # release +0.2.0-a.0.20180319252139.d923274528eb # snapshot (first in 0.2.0) +... +\ + +For a more detailed discussion of standard versioning and its support in +\c{build2} refer to \l{b#module-version Version Module}. -$ b config.cxx=g++-5 \ - config.cc.coptions=-O3 \ - config.import.libhello=/tmp/hello-gcc5-release \ - 'configure(hello2/@hello2-gcc5-release/)' +Let's now see how this works in practice by publishing a couple of versions +for our \c{hello} project. By now it should be clear what that +\c{0.1.0-a.0.19700101000000} means \- it is the first snapshot version of our +project. Since there are no commits yet, it has the UNIX epoch as its commit +timestamp. As the first step, let's try to commit our project and see what +changes: + +\ +$ git add . +$ git commit -m \"Start hello project\" -mkdir -p hello2-gcc5-release/build/ -save hello2-gcc5-release/build/config.build +$ bdep status +hello configured 0.1.0-a.0.19700101000000 + available 0.1.0-a.0.20180507062614.ee006880fc7e \ -Translated, \c{configure(hello2/@hello2-gcc5-release/)} means \i{\"configure -the \c{hello2/} source directory in the \c{hello2-gcc5-release/} output -directory\"}. In \c{build2} this \i{source directory} is called \c{src_root} -and \i{output directory} \- \c{out_root}. Hm, we've already heard \c{out_root} -mentioned somewhere before... +Just like with changes to dependency information, \c{status} has detected that +a new (snapshot) version of our project is available for synchronization. -Once the configuration is saved, we can develop our project without any -annoyance: +\N|Another way to view the project's version (which works even if we are +not using \c{bdep}) is with the build system's \c{info} operation: \ -$ b hello2-gcc5-release/ -c++ hello2/cxx{hello} -ld hello2-gcc5-release/exe{hello} +$ b info +project: hello +version: 0.1.0-a.0.20180507062614.ee006880fc7e +summary: hello executable project +... +\ -$ cd hello2-gcc5-release/ +| -$ b -info: dir{./} is up to date +Let's synchronize with the default build configuration: -$ b clean -rm exe{hello} -rm obje{hello} +\ +$ bdep sync +synchronizing: + upgrade hello/0.1.0-a.0.20180507062614.ee006880fc7e -$ b -v -g++-5 -I/tmp/hello-gcc5-release/libhello-1.0.0 -O3 -std=c++11 -o hello.o -c ../hello2/hello.cpp -g++-5 -O3 -std=c++11 -o hello hello.o /tmp/hello-gcc5-release/libhello-1.0.0/hello/libhello-1.0.so +$ bdep status +hello configured 0.1.0-a.0.20180507062614.ee006880fc7e \ -Some of you might have noticed that \c{hello2-gcc5-release/} and -\c{/tmp/hello-gcc5-release/} look awfully similar and are now wondering if we -could instead build \c{hello2} \i{inside} \c{/tmp/hello-gcc5-release/}? I am -glad you've asked. In fact, we can just do: +\N|Notice that we didn't have to manually change the version anywhere. All we +had to do was commit our changes and a new snapshot version was automatically +derived by \c{build2} from the new \c{git} commit. Without this automation +continuous versioning would hardly be practical.| +If we now make another commit, we will see a similar picture: + +\ +$ bdep status +hello configured 0.1.0-a.0.20180507062614.ee006880fc7e + available 0.1.0-a.0.20180507062615.8fb9de05b38f \ -$ cd .. -$ ls -1F -hello2/ -hello2-gcc5-release/ -$ b 'configure(hello2/@/tmp/hello-gcc5-release/hello2/)' -mkdir -p /tmp/hello-gcc5-release/hello2/build/ -save /tmp/hello-gcc5-release/hello2/build/config.build +\N|Note that you don't need to manually run \c{sync} after every commit. As +discussed earlier, you can simply run the build system to update your project +and things will get automatically synchronized if necessary.| -$ b /tmp/hello-gcc5-release/hello2/ -c++ hello2/cxx{hello}@/tmp/hello-gcc5-release/hello2/ -ld /tmp/hello-gcc5-release/hello2/exe{hello} +Ok, time for our first release. Let's start with \c{0.1.0-a.1}. Unlike +snapshots, for pre-releases as well as final releases we have to update the +version in the \c{manifest} file manually: + +\ +version: 0.1.0-a.1 \ -Now that might seem like magic, but it's actually pretty logical. Why don't we -need to specify any of the \c{config.c*} values this time? Because they are -inherited from those specified for \c{/tmp/hello-gcc5-release} when we created -the configuration with \c{bpkg create}. What about \c{config.import.libhello}, -don't we need at least that? Not really \- \c{libhello} will be found -automatically since it is part of the same amalgamation. +\N|The \c{manifest} file is the singular place where we specify the package +version. The build system's \l{b#module-version \c{version} module} makes it +available in various forms in buildfiles and even source code.| + +To ensure continuous versioning, this change to version must be the last commit +for this (pre-)release which itself must be immediately followed by a second +change to the version starting the development of the next (pre-)release. We +also recommend that you tag the release commit with a tag name in the +\c{\b{v}\i{X}.\i{Y}.\i{Z}} form. + +\N|Having regular release tag names with the \cb{v} prefix allows one to +distinguish them from other tags, for example, with wildcard patterns.| -Of course, \c{bpkg} has no idea \c{hello2} is now part of its configuration: +Here is the release workflow for our example: \ -$ bpkg status -d /tmp/hello-gcc5-release/ hello2 -unknown +$ git commit -a -m \"Release version 0.1.0-a.1\" +$ git tag -a v0.1.0-a.1 -m \"Tag version 0.1.0-a.1\" +$ git push --follow-tags + +# Version 0.1.0-a.1 is now public. + +$ edit manifest # change 'version: 0.1.0-a.1.z' +$ git commit -a -m \"Change version to 0.1.0-a.1.z\" +$ git push + +# Master is now open for business. \ -This is what I meant when I said you can muck around in \c{bpkg}'s back yard as -long as you understand the implications. +\N|In the future release management will be automated with a +\c{bdep-release(1)} command.| -But is there a way to make \c{bpkg} aware of our little project? You seem to -really have all the right questions today. Actually, there is a very good -reason why we would want that: if we upgrade \c{libhello} we would want -\c{bpkg} to automatically reconfigure our project. As it is now, we will have -to remember and do it ourselves. +Notice also that when specifying a snapshot version in \c{manifest} we use the +special \cb{z} snapshot value (for example, \c{0.1.0-a.1.z}) which is +recognized and automatically replaced by \c{build2} with, in case of \c{git}, +a commit timestamp and id (refer to \l{b#module-version Version Module} for +details). -The only way to make \c{bpkg} aware of \c{hello2} is to turn it from merely a -\c{build2} \i{project} into a \c{build2} \i{package}. While the topic of -packaging is also for another time and place (the \c{build2} package manager -manual), we can get away with something as simple as this: +Publishing the final release is exactly the same. For completeness, here +are the commands: \ -$ cat >hello2/manifest -: 1 -name: hello2 -version: 1.0.0 -summary: Improved \"Hello World\" program -license: proprietary -url: http://example.org/hello2 -email: hello2@example.org -depends: libhello >= 1.0.0 +$ edit manifest # change 'version: 0.1.0' +$ git commit -a -m \"Release version 0.1.0\" +$ git tag -a v0.1.0 -m \"Tag version 0.1.0\" +$ git push --follow-tags + +$ edit manifest # change 'version: 0.2.0-a.0.z' +$ git commit -a -m \"Change version to 0.2.0-a.0.z\" +$ git push \ -For our purposes, the only really important value in this manifest is -\c{depends} since it tells \c{bpkg} which package(s) we need. Let's give it a -try. But first we will clean up our previous attempt at building \c{hello2} -inside \c{/tmp/hello-gcc5-release/}: +\N|One sticky point of continuous versioning is choosing the next version. +For example, above should we continue with \c{0.1.1-a.0}, \c{0.2.0-a.0}, +or \c{1.0.0-a.0}? The important rule to keep in mind is that we can jump +forward to any further version at any time and without breaking continuous +versioning. But we can never jump backwards. + +For example, we can start with \c{0.2.0-a.0} but if we later realize that this +will actually be a new major release, we can easily change it to +\c{1.0.0-a.0}. As a result, the general recommendation is to start +conservatively by either incrementing the patch or the minor version +component. The recommended strategy is to increment the minor component and, +if required, release patch versions from a separate branch (created by +branching off from the release commit). + +Note also that you don't have to make any pre-releases if you don't need them. +While during development you would still keep the version as \c{X.Y.Z-a.0}, at +release you simply change it directly to the final \c{X.Y.Z}.| + +When publishing the final release you may also want to clean up now +obsolete pre-release tags. For example: \ -$ b '{clean disfigure}(/tmp/hello-gcc5-release/hello2/)' -rm /tmp/hello-gcc5-release/hello2/exe{hello} -rm /tmp/hello-gcc5-release/hello2/obje{hello} -rm /tmp/hello-gcc5-release/hello2/build/config.build -rmdir /tmp/hello-gcc5-release/hello2/ +$ git tag -l 'v0.1.0-*' | xargs git push --delete origin +$ git tag -l 'v0.1.0-*' | xargs git tag --delete \ -Next, we use the \l{bpkg-pkg-build(1) \c{bpkg build}} command but instead of -giving it a package name like we did before, we will point it to our \c{hello2} -package directory (\c{bpkg} can fetch packages or it can build local package -archives or package directories): +\N|While at first removing such tags may seem like a bad idea, pre-releases +are by nature temporary and their use only makes sense until the final release +is published. + +Also note that having a \c{git} repository with a large number of published +but unused version tags may result in a significant download overhead.| + +Let's also briefly discuss in which situations we should increment each of the +version components. While \i{semver} gives basic guidelines, there are several +ways to apply them in the context of C/C++ where there is a distinction +between binary and source compatibility. We recommend that you reserve +\i{patch} releases for specific bug fixes and security issues that you can +guarantee with a high level of certainty to be binary-compatible. Otherwise, +if the changes are source-compatible, increment \i{minor}. And if they are +breaking (that is, the user code likely will need adjustments), increment +\i{major}. During early development, when breaking changes are frequent, it is +customary to use the \c{0.Y.Z} versions where \c{Y} effectively becomes the +\i{major} component. Again, refer to the \l{b#module-version Version Module} +for a more detailed discussion of this topic. + +\h#guide-consume-pkg|Package Consumption| + +Ok, now that we have published a few releases of \c{hello}, how would the +users of our project get them? While they could clone the repository and use +\c{bdep} just like we did, this is more of a development rather than +consumption workflow. For consumption it is much easier to use the package +dependency manager, \l{bpkg(1)}, directly. + +First, we create a suitable build configuration with the +\l{bpkg-cfg-create(1)} command. We can use the same place for building all our +tools so let's call the directory \c{tools}. Seeing that we are only +interested in using (rather than developing) such tools, let's build them +optimized and also configure a suitable installation location: \ -$ bpkg build -d /tmp/hello-gcc5-release/ ./hello2/ - build hello2/1.0.0 -continue? [Y/n] y -unpacked hello2/1.0.0 -configured hello2/1.0.0 -c++ hello2/cxx{hello}@/tmp/hello-gcc5-release/hello2-1.0.0/ -ld /tmp/hello-gcc5-release/hello2-1.0.0/exe{hello} -updated hello2/1.0.0 +$ bpkg create -d tools cc \ + config.cxx=g++ \ + config.cc.coptions=-O3 \ + config.install.root=/usr/local \ + config.install.sudo=sudo +created new configuration in /tmp/tools/ + +$ cd tools \ -Let's upgrade \c{libhello} and see what happens: +\N|The \c{bdep} build configurations we were creating with \c{init\ -C} are +actually \c{bpkg} build configurations. In fact, underneath, \l{bdep-init(1)} +calls \l{bpkg-cfg-create(1)}.| + +To fetch and build packages (as well as all their dependencies) we use the +\l{bpkg-pkg-build(1)} command. We can use either an archive-based repository +like \l{https://cppget.org cppget.org} or build directly from \c{git}: \ -$ bpkg build -d /tmp/hello-gcc5-release/ -L libhello - build libformat/1.0.0 (required by libhello) - build libprint/1.0.0 (required by libhello) - upgrade libhello/1.1.0 - reconfigure hello2 (dependent of libhello) +$ bpkg build hello@https://git.build2.org/hello/hello.git +fetching from https://git.build2.org/hello/hello.git + new libformat/1.0.0 (required by libhello) + new libprint/1.0.0 (required by libhello) + new libhello/1.1.0 (required by hello) + new hello/1.0.0 continue? [Y/n] y -disfigured hello2/1.0.0 -disfigured libhello/1.0.0 -[ ... fetching & unpacking ... ] configured libformat/1.0.0 configured libprint/1.0.0 configured libhello/1.1.0 -configured hello2/1.0.0 -[ ... updating libprint, libformat, and libhello ... ] -updated libhello/1.1.0 +configured hello/1.0.0 +c++ libprint-1.0.0/libprint/cxx{print} +c++ hello-1.0.0/hello/cxx{hello} +c++ libhello-1.1.0/libhello/cxx{hello} +c++ libformat-1.0.0/libformat/cxx{format} +ld libprint-1.0.0/libprint/libs{print} +ld libformat-1.0.0/libformat/libs{format} +ld libhello-1.1.0/libhello/libs{hello} +ld hello-1.0.0/hello/exe{hello} +updated hello/1.0.0 +\ + +\N|Passing a repository URL to the \c{build} command is a shortcut to the +following sequence of commands: + \ +$ bpkg add https://git.build2.org/hello/hello.git # add repository +$ bpkg fetch # fetch package list +$ bpkg build hello # build package by name +\ + +| -As promised, \c{hello2} got reconfigured (it didn't get updated because of the -\c{-L} option). We can now update it and give it a try: +Once built, we can install the package to the location that we have specified +with \c{config.install.root} using the \l{bpkg-pkg-install(1)} command: \ -$ bpkg update -d /tmp/hello-gcc5-release/ hello2 -c++ hello2/cxx{hello}@/tmp/hello-gcc5-release/hello2-1.0.0/ -ld /tmp/hello-gcc5-release/hello2-1.0.0/exe{hello} -updated hello2/1.0.0 +$ bpkg install hello +... +install libformat-1.0.0/libformat/libs{format} +install libprint-1.0.0/libprint/libs{print} +install libhello-1.1.0/libhello/libs{hello} +install hello-1.0.0/hello/exe{hello} -$ /tmp/hello-gcc5-release/hello2-1.0.0/hello +$ hello World Hello, World! \ -To finish off, let's see how hard it will be to get a Clang build going: +\N|If on your system the installed executables don't run from \c{/usr/local} +because of the unresolved shared libraries (or if you are installing somewhere +else, such as \c{/opt}), then the easiest way to fix this is with \i{rpath}. +Simply add the following configuration variable when creating the build +configuration (or as an argument to the \c{install} command): \ -$ cd /tmp -$ mkdir hello-clang36-release -$ cd hello-clang36-release +config.bin.rpath=/usr/local/lib +\ -$ bpkg create cc config.cxx=clang++-3.6 config.cc.coptions=-O3 -created new configuration in /tmp/hello-clang36-release/ +| -$ bpkg add https://build2.org/pkg/1/hello/testing -added repository build2.org/hello/testing +If we need to uninstall a previously installed package, there is the +\l{bpkg-pkg-uninstall(1)} command: -$ bpkg fetch -fetching build2.org/hello/testing -[... certificate authentication ...] -fetching build2.org/hello/stable (complements build2.org/hello/testing) -5 package(s) in 2 repository(s) - -$ bpkg build libhello/1.0.0 path/to/hello2/ - build libhello/1.0.0 - build hello2/1.0.0 -continue? [Y/n] y -libhello-1.0.0.tar.gz 100% of 2428 B 983 kBps 00m01s -fetched libhello/1.0.0 -unpacked libhello/1.0.0 -unpacked hello2/1.0.0 -configured libhello/1.0.0 -configured hello2/1.0.0 -c++ libhello-1.0.0/hello/cxx{hello} -ld libhello-1.0.0/hello/liba{hello} -c++ libhello-1.0.0/hello/cxx{hello} -ld libhello-1.0.0/hello/libs{hello} -c++ libhello-1.0.0/tests/test/cxx{driver} -ld libhello-1.0.0/tests/test/exe{driver} -c++ /path/to/hello2/cxx{hello}@hello2-1.0.0/ -ld hello2-1.0.0/exe{hello} -updated libhello/1.0.0 -updated hello2/1.0.0 +\ +$ bpkg uninstall hello +uninstall hello-1.0.0/hello/exe{hello} +uninstall libhello-1.1.0/libhello/libs{hello} +uninstall libprint-1.0.0/libprint/libs{print} +uninstall libformat-1.0.0/libformat/libs{format} +... \ -Are you still there? Ok, one last example. Let's see how hard it is to -cross-compile. +To upgrade or downgrade packages we again use the \c{build} command. Here +is a typical upgrade workflow: \ -$ mkdir hello-mingw64 -$ cd hello-mingw64 +$ bpkg fetch # refresh available package list +$ bpkg status # see if new versions are available -$ bpkg create cc config.cxx=x86_64-w64-mingw32-g++ -created new configuration in /tmp/hello-mingw64/ +$ bpkg uninstall hello # uninstall old version +$ bpkg build hello # upgrade to the latest version +$ bpkg install hello # install new version +\ -$ bpkg add https://build2.org/pkg/1/hello/stable -added repository build2.org/hello/stable +Similar to \c{bdep}, to downgrade we have to specify the desired version +explicitly. There are also the \c{--upgrade|-u} and \c{--patch|-p} as well as +\c{--immediate|-i} and \c{--recursive|-r} options that allow us to upgrade or +patch packages that we have built and/or their immediate or all dependencies +(see \l{bpkg-pkg-build(1)} for details). For example, to make sure everything +is patched, run: +\ $ bpkg fetch -fetching build2.org/hello/stable -[... certificate authentication ...] -2 package(s) in 1 repository(s) - -$ bpkg build -y hello -libhello-1.0.0.tar.gz 100% of 2428 B 983 kBps 00m01s -fetched libhello/1.0.0 -unpacked libhello/1.0.0 -hello-1.0.0.tar.gz 100% of 1057 B 6882 kBps 00m01s -fetched hello/1.0.0 -unpacked hello/1.0.0 -configured libhello/1.0.0 -configured hello/1.0.0 -c++ hello-1.0.0/cxx{hello} -c++ libhello-1.0.0/hello/cxx{hello} -ld libhello-1.0.0/hello/libs{hello} -ld hello-1.0.0/exe{hello} -updated hello/1.0.0 - -$ wine hello-1.0.0/hello.exe Windows -Hello, Windows! +$ bpkg build -pr \ -In fact, on a properly setup GNU/Linux machine (that automatically uses -\c{wine} as an \c{.exe} interpreter) we can even run tests: +If a package is no longer needed, we can remove it from the configuration with +\l{bpkg-pkg-drop(1)}: \ -$ bpkg test libhello hello -c++ libhello-1.0.0/tests/test/cxx{driver} -ld libhello-1.0.0/tests/test/exe{driver} -test libhello-1.0.0/tests/test/exe{driver} -test hello-1.0.0/exe{hello} -tested libhello/1.0.0 -tested hello/1.0.0 +$ bpkg drop hello +following dependencies were automatically built but +will no longer be used: + libhello + libformat + libprint +drop unused packages? [Y/n] y + drop hello + drop libhello + drop libformat + drop libprint +continue? [Y/n] y +purged hello +purged libhello +purged libformat +purged libprint \ " diff --git a/doc/intro1.cli b/doc/intro1.cli new file mode 100644 index 0000000..f53544d --- /dev/null +++ b/doc/intro1.cli @@ -0,0 +1,1169 @@ +// file : doc/intro1.cli +// copyright : Copyright (c) 2014-2017 Code Synthesis Ltd +// license : MIT; see accompanying LICENSE file + +"\name=build2-toolchain-intro" +"\subject=toolchain" +"\title=Toolchain Introduction" + +// TODO +// +// @@ refs to further docs +// +// STYLE +// +// @@ section boundary page breaks (
) +// @@ when printed, code background is gone, but spaces still there +// +// PDF +// +// @@ tree output is garbled +// @@ Install list margins missing +// @@ Could we use a nicer font, seeing that we embed them? +// + +// NOTES +// +// - Maximum 
 line is 70 characters.
+//
+
+"
+\h#tldr|TL;DR|
+
+\
+$ bpkg create -d hello cc
+created new configuration in hello/
+
+$ cd hello/
+$ bpkg add https://build2.org/pkg/1/hello/stable
+added repository build2.org/hello/stable
+
+$ bpkg fetch
+fetching build2.org/hello/stable
+2 package(s) in 1 repository(s)
+
+$ bpkg build hello
+  build libhello/1.0.0 (required by hello)
+  build hello/1.0.0
+continue? [Y/n] y
+
+libhello-1.0.0.tar.gz        100% of 2428  B  983 kBps 00m01s
+fetched libhello/1.0.0
+unpacked libhello/1.0.0
+
+hello-1.0.0.tar.gz           100% of 1057  B 6882 kBps 00m01s
+fetched hello/1.0.0
+unpacked hello/1.0.0
+
+configured libhello/1.0.0
+configured hello/1.0.0
+
+c++ hello-1.0.0/cxx{hello}
+c++ libhello-1.0.0/hello/cxx{hello}
+ld libhello-1.0.0/hello/libs{hello}
+ld hello-1.0.0/exe{hello}
+
+updated hello/1.0.0
+\
+"
+
+"
+\h#warning|Warning|
+
+The \c{build2} toolchain \c{0.X.Y} series are alpha releases. Interfaces
+\i{will} most likely change in backwards-incompatible ways. But if you want
+to start playing with it, welcome and join the \l{https://lists.build2.org
+mailing list}!
+
+Our approach to developing \c{build2} is to first get the hard parts right
+before focusing on completeness. So while we might still have no support for
+custom build rules, we do handle auto-generated source code (and, in
+particular, headers) properly. In other words, we go depth rather than
+breadth-first. As a result, there are some limitations and missing pieces,
+especially in the build system. The most notable ones are:
+
+\ul|
+
+\li|Limited documentation.|
+
+\li|No support for custom build system rules/modules.|
+
+|
+"
+
+"
+\h#intro|Introduction|
+
+The \c{build2} toolchain is a set of tools designed for building and packaging
+C and C++ code (though, if it can handle C++, it can handle anything,
+right?). The toolchain currently includes the \i{build system} (\c{build2}),
+the \i{package manager} (\c{bpkg}), and the \i{repository web interface}
+(\c{brep}). More tools, such as the \i{build robot} (\c{bbot}), are in the
+works. Then there is \l{https://cppget.org/ cppget.org} (running \c{brep})
+which we hope will become \i{the C++ package repository}.
+
+The goal of this document is to give you a basic idea of what the \c{build2}
+toolchain can do so that you can decide if you are interested and want to learn
+more. Further documentation is referenced at the end of this introduction.
+
+The \c{build2} toolchain is self-hosted and self-packaged (and, yes, it is on
+\l{https://cppget.org/ cppget.org}). It could have served as its own example,
+however, before the toolchain can build itself, we have to bootstrap it (that
+chicken and egg problem again). And this step wouldn't serve our goal of
+quickly learning what \c{build2} is about. So, instead, we will start with a
+customary \i{\"Hello, World!\"} example which you won't yet be able to try
+yourself (but don't worry, complete terminal output will be shown). If at the
+end you find \c{build2} appealing, you can jump straight to
+\l{build2-toolchain-install.xhtml The \c{build2} Toolchain Installation and
+Upgrade} (and, yes, there you get to run that coveted \c{bpkg build bpkg}).
+Once the \c{build2} installation is complete, you can come back to the
+\i{\"Hello, World!\"} example and try all of the steps for yourself.
+
+This introduction explores the \i{consumer} side of \i{\"Hello, World!\"}.
+That is, we assume that someone was kind enough to create and package the
+\c{libhello} library as well as the \c{hello} program and we will learn how to
+obtain and build them as well as keep up with their updates. At the end we
+will also see how to write our own, \c{hello2}, program that depends on
+\c{libhello}.  And so, without further ado, let's begin.
+
+Actually, one more thing: if you have a recent enough compiler and would like
+to try the new C++ Modules support, then you can instead use the modularized
+variants of these packages: simply replace \c{hello} with \c{mhello} and
+\c{libhello} with \c{libmhello} in the commands below.
+
+The first step in using \c{bpkg} is to create a \i{configuration}. A
+configuration is a directory where packages that require similar compile
+settings will be built. You can create as many configurations as you want: for
+different C++ compilers, targets (\c{build2} is big on cross-compiling),
+debug/release, 32/64-bit, or even for different days of the week, if you are
+so inclined. Say we are in the mood for a GCC 5 release build today:
+
+\
+$ mkdir hello-gcc5-release
+$ cd hello-gcc5-release
+$ bpkg create cxx config.cxx=g++-5 config.cxx.coptions=-O3
+created new configuration in /tmp/hello-gcc5-release/
+\
+
+Or perhaps you are on Windows and prefer Visual Studio (running from the
+Visual Studio Tools Command Prompt):
+
+\
+> mkdir hello-vc14-release
+> cd hello-vc14-release
+> bpkg create cxx config.cxx=cl config.cxx.coptions=/O2
+created new configuration in C:\projects\hello-vc14-release\
+\
+
+One of the primary goals of the \c{build2} toolchain is to provide a uniform
+build interface across all the platforms and compilers. While the following
+examples use the \c{hello-gcc5-release} configuration and assume a UNIX-like
+operation system, everything will work if you use \c{hello-vc14-release} (or
+\c{hello-mingw-release}) on Windows. Just use appropriate paths, compilers,
+and options.
+
+Let's discuss that last command line: \l{bpkg-cfg-create(1) \c{bpkg create}}
+is the command for creating a new configuration. As a side note, if you ever
+want to get help for any \c{bpkg} command, run \c{bpkg help \i{}}. To
+see the list of commands, run just \l{bpkg-help(1) \c{bpkg help}} (or see
+\l{bpkg(1)}). While we are at it, if you ever want to see what \c{bpkg} is
+running underneath, there is the \c{-v} (essential commands) and \c{-V} (all
+commands) options. And if you really want to get under the hood, use
+\l{bpkg-common-options(1) \c{--verbose }}.
+
+After the command we have \c{cxx} which is the name of the \c{build2} build
+system module. As you might have guessed, \c{cxx} provides support for the C++
+compilation. By specifying this module when creating the configuration we
+configure it (yes, with those \c{config.cxx.*} variables that follow) for the
+entire configuration. That is, every package that we will build in this
+configuration and that uses the \c{cxx} module will by default inherit these
+settings.
+
+The rest of the command line are the configuration variables for the \c{cxx}
+module with \c{coptions} standing for \i{compile options} (there are also
+\c{poptions} for \i{preprocess options}, \c{loptions} for \i{link options}, and
+\c{libs} for extra libraries to link).
+
+There is also the \c{c} module for the C compilation. So if we were planning
+to build both C and C++ projects, then we could have run:
+
+\
+$ bpkg create c cxx ...
+\
+
+The problem, of course, is that you may not know what mix of languages those
+projects (or their dependencies) might use. For example, the use of C might be
+an implementation detail of a C++ library. To solve this, \c{build2} provides
+another module called \c{cc} which stands for \i{C-common}. So, in this
+context, instead of using the \c{c} and \c{cxx} modules directly, it's a good
+idea to get into the habit of using \c{cc}:
+
+\
+$ bpkg create cc config.cxx=g++-5 config.cc.coptions=-O3
+\
+
+Notice two things about this command line: we don't need to specify the C
+compiler with \c{config.c} \- \c{build2} is smart enough to figure it out
+from \c{config.cxx} (or vice versa). We also used \c{config.cc.coptions}
+instead of \c{config.cxx.coptions} so that the options apply to all the
+C-common languages (we can still use \c{config.{c,cxx\}.*} for the
+language-specific options).
+
+Ok, configuration in hand, where can we get some packages? \c{bpkg} packages
+come from \i{repositories}. A repository can be a local filesystem directory
+or a remote URL. Our example packages come from their own remote \i{\"Hello,
+World!\"} repository: \c{\l{https://build2.org/pkg/1/hello/stable/}} (go ahead,
+browse it, I will wait).
+
+Instead of scouring repository manifests by hand (I know you couldn't resist),
+we can ask \c{bpkg} to interrogate a repository location for us:
+
+\
+$ bpkg rep-info https://build2.org/pkg/1/hello/stable
+warning: authenticity of the certificate for repository build2.org/hello/stable cannot be established
+certificate is for build2.org, \"Code Synthesis\" 
+certificate SHA256 fingerprint:
+FF:DF:7D:38:67:4E:C3:82:[...]:30:56:B9:77:B9:F2:01:94
+trust this certificate? [y/n]
+\
+
+The \c{bpkg} repositories are normally signed to prevent tampering with
+packages. If the repository certificate is seen (in this configuration) for
+the first time, \c{bpkg} will ask you to authenticate it. A good way to
+authenticate a certificate is to compare the displayed fingerprint to the one
+you have received earlier, for example, in an email announcement. The
+repository's about page also lists the fingerprint (see the
+\l{https://build2.org/pkg/hello/?about about page} for our repository). For
+more details on repository signing see the \l{bpkg-repository-signing(1)} help
+topic.
+
+If we answer \i{yes}, we will see the basic repository information (its
+\i{canonical name}, location, certificate subject and fingerprint) followed
+by the list of available packages:
+
+\
+build2.org/hello/stable https://build2.org/pkg/1/hello/stable
+CN=build2.org/O=Code Synthesis/admin@build2.org
+FF:DF:7D:38:67:4E:C3:82:[...]:30:56:B9:77:B9:F2:01:94
+
+hello/1.0.0
+libhello/1.0.0
+\
+
+We can also use the repository's web interface (implemented by \c{brep}). Our
+repository has one, check it out: \c{\l{https://build2.org/pkg/hello/}}.
+
+Ok, back to the command line. If we want to use a repository as a source of
+packages in our configuration, we have to first add it:
+
+\
+$ bpkg add https://build2.org/pkg/1/hello/stable
+added repository build2.org/hello/stable
+\
+
+If we want to add several repositories, we just execute the \l{bpkg-rep-add(1)
+\c{bpkg add}} command for each of them. Once this is done, we fetch the list of
+available packages for all the added repositories:
+
+\
+$ bpkg fetch
+fetching build2.org/hello/stable
+2 package(s) in 1 repository(s)
+\
+
+Note that you would normally re-run the \l{bpkg-rep-fetch(1) \c{bpkg fetch}}
+command after you've added another repository or to refresh the list of
+available packages.
+
+Now that \c{bpkg} knows where to get the packages, we can finally get down to
+business:
+
+\
+$ bpkg build hello
+  build libhello/1.0.0 (required by hello)
+  build hello/1.0.0
+continue? [Y/n]
+\
+
+Let's see what's going on here. We ran \l{bpkg-pkg-build(1) \c{bpkg build}} to
+build the \c{hello} program which happens to depend on the \c{libhello}
+library. So \c{bpkg} presents us with a \i{plan of action}, that is, the steps
+it will have to perform in order to build us \c{hello} and then asks us to
+confirm if that's what we want to do (you can add \c{--yes|-y} to skip the
+confirmation). In the real-world usage the plan will be more complex, with
+upgrades/downgrades, reconfigurations, etc.
+
+Let's answer \i{yes} and see what happens:
+
+\
+libhello-1.0.0.tar.gz        100% of 2428  B 1364 kBps 00m01s
+fetched libhello/1.0.0
+unpacked libhello/1.0.0
+hello-1.0.0.tar.gz           100% of 1057  B   20 MBps 00m01s
+fetched hello/1.0.0
+unpacked hello/1.0.0
+configured libhello/1.0.0
+configured hello/1.0.0
+c++ hello-1.0.0/cxx{hello}
+c++ libhello-1.0.0/hello/cxx{hello}
+ld libhello-1.0.0/hello/libs{hello}
+ld hello-1.0.0/exe{hello}
+updated hello/1.0.0
+\
+
+While the output is mostly self-explanatory, in short, \c{bpkg} downloaded,
+unpacked, and configured both packages and then proceeded to building the
+\c{hello} executable which happens to require building the \c{libhello}
+library. Note that the download progress may look differently on your machine
+depending on which \i{fetch tool} (\c{wget}, \c{curl}, or \c{fetch}) is
+used. If you ever considered giving that \c{-v} option a try, now would be a
+good time. But let's first drop (\l{bpkg-pkg-drop(1) \c{bpkg drop}}) the
+\c{hello} package so that we get the same build from scratch:
+
+\
+$ bpkg drop hello
+following prerequisite packages were automatically built and will no longer be necessary:
+  libhello
+drop prerequisite packages? [Y/n] y
+  drop hello
+  drop libhello
+continue? [Y/n] y
+disfigured hello
+disfigured libhello
+purged hello
+purged libhello
+\
+
+Ok, ready for some \c{-v} details? Feel free to skip the following listing
+if you are not interested.
+
+\
+$ bpkg build -v -y hello
+fetching libhello-1.0.0.tar.gz from build2.org/hello/stable
+curl ... https://build2.org/pkg/1/hello/stable/libhello-1.0.0.tar.gz
+  % Total    % Received Average Speed   Time    Time     Time  Current
+                        Dload  Upload   Total   Spent    Left  Speed
+100  2428  100  2428      1121      0  0:00:01  0:00:01 --:--:--  1122
+fetched libhello/1.0.0
+tar -xf libhello-1.0.0.tar.gz
+unpacked libhello/1.0.0
+fetching hello-1.0.0.tar.gz from build2.org/hello/stable
+curl ... https://build2.org/pkg/1/hello/stable/hello-1.0.0.tar.gz
+  % Total    % Received Average Speed   Time    Time     Time  Current
+                        Dload  Upload   Total   Spent    Left  Speed
+100  1057  100  1057      773      0  0:00:01  0:00:01 --:--:--   772
+fetched hello/1.0.0
+tar -xf hello-1.0.0.tar.gz
+unpacked hello/1.0.0
+b -v configure(./libhello-1.0.0/)
+cat >libhello-1.0.0/build/config.build
+configured libhello/1.0.0
+b -v configure(./hello-1.0.0/)
+cat >hello-1.0.0/build/config.build
+configured hello/1.0.0
+hold package hello
+b -v update(./hello-1.0.0/)
+g++-5 -I libhello-1.0.0 -O3 -std=c++11 -o hello-1.0.0/hello.o -c hello-1.0.0/hello.cxx
+g++-5 -I libhello-1.0.0 -O3 -std=c++11 -fPIC -o libhello-1.0.0/hello/hello.so.o -c libhello-1.0.0/hello/hello.cxx
+g++-5 -O3 -std=c++11 -shared -o libhello-1.0.0/hello/libhello-1.0.so libhello-1.0.0/hello/hello.so.o
+g++-5 -O3 -std=c++11 -o hello-1.0.0/hello hello-1.0.0/hello.o libhello-1.0.0/hello/libhello-1.0.so
+updated hello/1.0.0
+\
+
+Another handy command is \l{bpkg-pkg-status(1) \c{bpkg status}}. It can be
+used to examine the state of a package in the configuration. Here are a few
+examples (if you absolutely must know what \c{hold_package} and \c{sys:?}
+mean, check \l{bpkg-pkg-status(1)}):
+
+\
+$ bpkg status libhello
+configured 1.0.0; available sys:?
+
+$ bpkg status hello
+configured 1.0.0 hold_package; available sys:?
+
+$ bpkg drop -y hello
+disfigured hello
+disfigured libhello
+purged hello
+purged libhello
+
+$ bpkg status hello
+available 1.0.0 sys:?
+
+$ bpkg status libfoobar
+unknown
+\
+
+Let's say we got wind of a new development: the \c{libhello} author released a
+new version of the library. It is such an advance in the art of \i{\"Hello,
+World!\"}, it's only currently available from \c{testing}. Of course, we must
+check it out.
+
+Now, what exactly is \c{testing}? You must have noticed that the repository
+location that we've been using so far ended with \c{/stable}. Quite often it is
+useful to split our repository into sub-repositories or \i{sections}. For
+example, to reflect the maturity of packages (say, \c{stable} and \c{testing},
+as in our case) or to divide them into sub-categories (\c{misc} and \c{math})
+or even some combination (\c{math/testing}). Note, however, that to \c{bpkg}
+these sub-repositories or \i{sections} are just normal repositories and there
+is nothing special about them.
+
+We are impatient to try the new version so we will skip interrogating the
+repository with \c{rep-info} and just add it to our configuration. After all,
+we can always check with \c{status} if any upgrades are available for packages
+we are interested in. Here we assume the configuration has \c{hello} built (run
+\c{bpkg build -y hello} to get to that state).
+
+\
+$ bpkg add https://build2.org/pkg/1/hello/testing
+added repository build2.org/hello/testing
+
+$ bpkg fetch
+fetching build2.org/hello/stable
+fetching build2.org/hello/testing
+5 package(s) in 2 repository(s)
+\
+
+Notice that this time we don't see any authentication-related messages or
+prompts since \c{bpkg} remembered (in this configuration) that we trust the
+certificate (\c{testing} naturally uses the same one as \c{stable}).
+
+Let's see what's new:
+
+\
+$ bpkg status libhello
+configured 1.0.0; available 1.1.0 sys:?
+\
+
+Ok, \c{libhello/1.1.0} is now available. How do we upgrade? We can try to
+build \c{hello} again:
+
+\
+$ bpkg build -y hello
+info: dir{hello-1.0.0/} is up to date
+updated hello/1.0.0
+\
+
+Why did nothing happen? Because \c{bpkg} will only upgrade (or downgrade)
+to a new version if we explicitly ask it to. As things stand, all dependencies
+for \c{hello} are satisfied and \c{bpkg} is happy to twiddle its thumbs. Let's
+tell \c{bpkg} to build us \c{libhello} instead:
+
+\
+$ bpkg build libhello
+  build libformat/1.0.0 (required by libhello)
+  build libprint/1.0.0 (required by libhello)
+  upgrade libhello/1.1.0
+  reconfigure hello (dependent of libhello)
+continue? [Y/n]
+\
+
+Ok, now we are getting somewhere. It looks like the new version of \c{libhello}
+went really enterprise-grade (or is it called web-scale these days?). There are
+now two new dependencies (\c{libformat} and \c{libprint}) that we will have to
+build in order to upgrade. Maybe we should answer \i{no} here?
+
+Notice also that \c{reconfigure hello} line. If you think about this, it makes
+sense: we are getting a new version of \c{libhello} and \c{hello} depends on it
+so it might need a chance to make some adjustments to its configuration.
+
+Let's answer \i{yes} if only to see what happens:
+
+\
+update dependent packages? [Y/n]
+\
+
+Another question. This one has to do with that \c{reconfigure hello} line we
+just talked about. If you were wondering why we were only offered to
+reconfigure and not actually update the dependent package, you should know
+that \c{bpkg} is a very lazy package manager, it only does what it must do,
+not what might be nice to do. It must reconfigure but it doesn't really have
+to update. And this could be a good thing if, for example, you have a hundred
+dependents in your configuration but right now you only want to build just
+those specific packages. However, quite often, you do want to keep all the
+packages in your configuration up to date and \c{bpkg} graciously offers to
+take care of this task. Ok, let's answer \i{yes} again:
+
+\
+...
+update dependent packages? [Y/n] y
+disfigured hello/1.0.0
+disfigured libhello/1.0.0
+libformat-1.0.0.tar.gz       100% of 1064  B   11 MBps 00m01s
+fetched libformat/1.0.0
+unpacked libformat/1.0.0
+libprint-1.0.0.tar.gz        100% of 1040  B    9 MBps 00m01s
+fetched libprint/1.0.0
+unpacked libprint/1.0.0
+libhello-1.1.0.tar.gz        100% of 1564  B 4672 kBps 00m01s
+fetched libhello/1.1.0
+unpacked libhello/1.1.0
+configured libformat/1.0.0
+configured libprint/1.0.0
+configured libhello/1.1.0
+configured hello/1.0.0
+c++ libhello-1.1.0/hello/cxx{hello}
+c++ libformat-1.0.0/format/cxx{format}
+ld libformat-1.0.0/format/liba{format}
+c++ libprint-1.0.0/print/cxx{print}
+ld libprint-1.0.0/print/liba{print}
+ld libhello-1.1.0/hello/liba{hello}
+c++ libhello-1.1.0/hello/cxx{hello}
+c++ libformat-1.0.0/format/cxx{format}
+ld libformat-1.0.0/format/libs{format}
+c++ libprint-1.0.0/print/cxx{print}
+ld libprint-1.0.0/print/libs{print}
+ld libhello-1.1.0/hello/libs{hello}
+c++ libhello-1.1.0/tests/test/cxx{driver}
+ld libhello-1.1.0/tests/test/exe{driver}
+c++ hello-1.0.0/cxx{hello}
+ld hello-1.0.0/exe{hello}
+updated libhello/1.1.0
+updated hello/1.0.0
+\
+
+A lot of output but nothing really new. If you were to answer \i{no} to the
+\"update dependent packages?\" question above, it is easy to make sure a
+package is up-to-date at a later time with the \l{bpkg-pkg-update(1) \c{bpkg
+update}} command (there is also \l{bpkg-pkg-clean(1) \c{bpkg clean}}), for
+example:
+
+\
+$ bpkg clean hello
+rm hello-1.0.0/exe{hello}
+rm hello-1.0.0/obje{hello}
+cleaned hello/1.0.0
+
+$ bpkg update hello
+c++ hello-1.0.0/cxx{hello.cxx}
+ld hello-1.0.0/exe{hello}
+updated hello/1.0.0
+\
+
+Let's say we really don't like the direction \c{libhello} is going and would
+rather stick to version \c{1.0.0}. Just like upgrades, downgrades are explicit
+plus, in this case, we need to specify the version (you can also specify
+the desired version for upgrades).
+
+\
+$ bpkg build libhello/1.0.0
+  downgrade libhello/1.0.0
+  reconfigure hello (dependent of libhello)
+continue? [Y/n] y
+update dependent packages? [Y/n] y
+disfigured hello/1.0.0
+disfigured libhello/1.1.0
+libhello-1.0.0.tar.gz        100% of 2428  B  983 kBps 00m01s
+fetched libhello/1.0.0
+unpacked libhello/1.0.0
+configured libhello/1.0.0
+configured hello/1.0.0
+following prerequisite packages were automatically built and will no longer be necessary:
+  libprint
+  libformat
+drop prerequisite packages? [Y/n] y
+disfigured libprint
+disfigured libformat
+purged libprint
+purged libformat
+c++ libhello-1.0.0/hello/cxx{hello}
+ld libhello-1.0.0/hello/liba{hello}
+c++ libhello-1.0.0/hello/cxx{hello}
+ld libhello-1.0.0/hello/libs{hello}
+c++ libhello-1.0.0/tests/test/cxx{driver}
+ld libhello-1.0.0/tests/test/exe{driver}
+c++ hello-1.0.0/cxx{hello}
+ld hello-1.0.0/exe{hello}
+updated libhello/1.0.0
+updated hello/1.0.0
+\
+
+Notice how \c{bpkg} helpfully offered to get rid of \c{libprint} and
+\c{libformat} which we won't be needing anymore. Note also that while we
+can use \c{--yes|y} as an answer to all the numerous prompts, there are
+also more granular options. For example, this is how we can instruct
+\c{bpkg} to drop prerequisites (\c{--drop-prerequisite|-D}) but leave
+dependents just reconfigured (\c{--leave-dependent|-L}):
+
+\
+$ bpkg build -D -L libhello/1.0.0
+\
+
+Ok, so all this might look nice and all, but we haven't actually seen anything
+of what we've presumably built; it can all be a charade, for all we know. Can
+we see some libraries and run the \c{hello} program?
+
+There are several ways we can do this. If the package provides tests (as all
+good packages should), we can run them with the \l{bpkg-pkg-test(1) \c{bpkg
+test}} command:
+
+\
+$ bpkg test libhello hello
+test libhello-1.0.0/tests/test/exe{driver}
+test hello-1.0.0/exe{hello}
+tested libhello/1.0.0
+tested hello/1.0.0
+\
+
+But that doesn't quite count for seeing libraries and running programs. Well,
+if you insist, let's see what's inside \c{hello-gcc5-release/}. The \c{bpkg}
+configuration (this \c{hello-gcc5-release/} directory) is, in the \c{build2}
+build system terms, an \i{amalgamation} \- a project that contains
+\i{subprojects}. Not surprisingly, the subprojects in this amalgamation are the
+packages that we've built:
+
+\
+$ ls -1F
+build/
+hello-1.0.0/
+libhello-1.0.0/
+buildfile
+hello-1.0.0.tar.gz
+libhello-1.0.0.tar.gz
+\
+
+And if we look inside \c{hello-1.0.0/} we will see what looks like the
+\c{hello} program:
+
+\
+$ ls -1F hello-1.0.0/
+build/
+buildfile
+hello*
+hello.d
+hello.cxx
+hello.o
+hello.o.d
+manifest
+test.out
+version
+
+$ hello-1.0.0/hello
+usage: hello ...
+
+$ hello-1.0.0/hello World
+Hello, World!
+\
+
+The important point here is this: the \c{bpkg} configuration is not some black
+box that you should never look inside of. On the contrary, it is a normal and
+predictable concept of the build system and as long as you understand what you
+are doing, feel free to muck around.
+
+Another way to get hold of a package's goodies is to install it with
+\l{bpkg-pkg-install(1) \c{bpkg install}}. Let's try that:
+
+\
+$ bpkg install                   \
+  config.install.root=/opt/hello \
+  config.install.sudo=sudo       \
+  hello
+
+install /opt/hello/
+install /opt/hello/include/
+install /opt/hello/include/hello/
+install libhello-1.0.0/hello/hxx{hello}
+install libhello-1.0.0/hello/hxx{export}
+install /opt/hello/lib/
+install libhello-1.0.0/hello/libs{hello}
+install /opt/hello/bin/
+install hello-1.0.0/exe{hello}
+install /opt/hello/share/
+install /opt/hello/share/doc/
+install /opt/hello/share/doc/hello/
+install hello-1.0.0/doc{version}
+installed hello/1.0.0
+\
+
+The \c{config.install.sudo} value is the optional \i{sudo}-like program
+that should be used to run the \c{install} program. For those feeling queasy
+running \c{sudo make install}, here is your answer. If you are wondering
+whether you could have specified those \c{config.install.*} values during the
+configuration creation, the answer is yes, indeed!
+
+Let's see what we've got:
+
+\
+$ tree -F /opt/hello/
+/opt/hello/
+├── bin/
+│   └── hello*
+├── include/
+│   └── libhello/
+│       ├── export
+│       └── hello
+├── lib/
+│   ├── libhello-1.0.so*
+│   └── libhello.so -> libhello-1.0.so*
+└── share/
+    └── doc/
+        └── hello/
+            └── version
+\
+
+We can also try to run the installed program:
+
+\
+$ /opt/hello/bin/hello World
+/opt/hello/bin/hello: error while loading shared libraries: libhello-1.0.so: cannot open shared object file: No such file or directory
+\
+
+Not what we hoped to see. Note to the Windows users: this will actually work
+since \c{hello-1.0.dll} will be installed into \c{bin\\}, next to the
+executable; for once things are working better on Windows.
+
+The problem is with our installation location: the runtime linker won't look
+for \c{libhello-1.0.so} in \c{/opt/hello/lib} unless we somehow tell it to
+(for example, using \c{LD_LIBRARY_PATH} or equivalent).  There are several
+ways we can resolve this. We could give up on shared libraries and link our
+prerequisite libraries statically (\c{config.bin.exe.lib=static}). Or we could
+use the \i{rpath} mechanism:
+
+\
+$ bpkg install                    \
+  config.install.root=/opt/hello  \
+  config.install.sudo=sudo        \
+  config.bin.rpath=/opt/hello/lib \
+  hello
+
+ld hello-1.0.0/exe{hello}
+install /opt/hello/
+install /opt/hello/include/
+install /opt/hello/include/hello/
+install libhello-1.0.0/hello/hxx{hello}
+install libhello-1.0.0/hello/hxx{export}
+install /opt/hello/lib/
+install libhello-1.0.0/hello/libs{hello}
+install /opt/hello/bin/
+install hello-1.0.0/exe{hello}
+install /opt/hello/share/
+install /opt/hello/share/doc/
+install /opt/hello/share/doc/hello/
+install hello-1.0.0/doc{version}
+installed hello/1.0.0
+
+$ /opt/hello/bin/hello World
+Hello, World!
+\
+
+Notice that \c{ld} line above \- this is where our executable is re-linked
+with the \c{-rpath} option.
+
+We can also uninstall what we have installed with \l{bpkg-pkg-uninstall(1)
+\c{bpkg uninstall}}:
+
+\
+$ bpkg uninstall                  \
+  config.install.root=/opt/hello  \
+  config.install.sudo=sudo        \
+  hello
+
+uninstall hello-1.0.0/doc{version}
+uninstall /opt/hello/share/doc/hello/
+uninstall /opt/hello/share/doc/
+uninstall /opt/hello/share/
+uninstall hello-1.0.0/exe{hello}
+uninstall /opt/hello/bin/
+uninstall libhello-1.0.0/hello/libs{hello}
+uninstall /opt/hello/lib/
+uninstall libhello-1.0.0/hello/hxx{export}
+uninstall libhello-1.0.0/hello/hxx{hello}
+uninstall /opt/hello/include/hello/
+uninstall /opt/hello/include/
+uninstall /opt/hello/
+uninstalled hello/1.0.0
+
+$ ls /opt/hello
+ls: cannot access /opt/hello: No such file or directory
+\
+
+What if we wanted to use \c{libhello} in our own project? While installing it
+is always an option, this may not be convenient when we develop our code. We
+may have multiple builds per project, for example, with GCC and Clang to catch
+all the warnings. We may also want to make sure our application works well
+with several versions of \c{libhello} (and maybe even with that heinous
+\c{1.1.X}). While we can install different configurations into different
+directories, it's hard to deny things are getting a bit hairy: multiple
+configurations, multiple installations... I guess we will have to get our
+hands into that cookie jar, I mean, configuration, again.
+
+In fact, let's just start writing our own version of the \c{hello} program
+and see how it goes:
+
+\
+$ mkdir hello2
+$ cd hello2
+
+$ cat >hello.cpp
+
+#include 
+
+int main ()
+{
+  hello::say (\"World\");
+}
+
+\
+
+What build system shall we use? I can't believe you are even asking this
+question...
+
+\
+$ mkdir build
+
+$ cat >build/bootstrap.build
+
+project = hello2              # project name
+using config                  # config module (those config.*)
+
+$ cat >build/root.build
+
+cxx.std = 11                  # C++ standard
+using cxx                     # C++ module
+cxx{*}: extension = cpp       # C++ source file extension
+
+$ cat >buildfile
+
+import libs = libhello%lib{hello}
+exe{hello}: cxx{hello} $libs
+\
+
+While some of this might not be crystal clear (like why do we have
+\c{bootstrap.build} \i{and} \c{root.build}), I am sure you at least have a
+fuzzy idea of what's going on. And that's enough for what we are after here.
+Completely explaining what's going on here and, more importantly, \i{why} it's
+going this way is for another time and place (the \c{build2} build system
+manual).
+
+To recap, these are the contents of our project so far:
+
+\
+$ tree -F
+.
+├── build/
+│   ├── bootstrap.build
+│   └── root.build
+├── buildfile
+└── hello.cpp
+\
+
+Let's try to build it and see what happens \- maybe it will magically work
+(\l{b(1)} is the \c{build2} build system driver).
+
+\
+$ b config.cxx=g++-5
+error: unable to import target libhello%lib{hello}
+  info: use config.import.libhello command line variable to specifying its project out_root
+  info: while applying rule cxx.link to update exe{hello}
+  info: while applying rule alias to update dir{./}
+\
+
+No magic, unfortunately (or fortunately). But we got a hint: looks like we
+need to tell \c{build2} where \c{libhello} is using
+\c{config.import.libhello}. Without fretting too much about what exactly
+\c{out_root} means, let's point \c{build2} to our \c{bpkg} configuration and
+see what happens. After all, that's where, more or less, our \i{out}-put for
+\c{libhello} is.
+
+\
+$ b config.cxx=g++-5 \
+    config.import.libhello=/tmp/hello-gcc5-release
+c++ cxx{hello}
+ld exe{hello}
+\
+
+Almost magic. Let's see what we've got:
+
+\
+$ tree -F
+.
+├── build/
+│   ├── bootstrap.build
+│   └── root.build
+├── buildfile
+├── hello*
+├── hello.d
+├── hello.cpp
+├── hello.o
+└── hello.o.d
+
+$ ./hello
+Hello, World!
+\
+
+Let's change something in our source code and try to update:
+
+\
+$ touch hello.cpp
+
+$ b
+error: unable to import target libhello%lib{hello}
+  info: use config.import.libhello command line variable to specifying its project out_root
+  info: while applying rule cxx.link to update exe{hello}
+  info: while applying rule alias to update dir{./}
+\
+
+Looks like we have to keep repeating those \c{config.*} values and who wants
+that? To get rid of this annoyance we have to make our configuration
+\i{permanent}. Also, seeing that we plan to have several of them (GCC/Clang,
+different version of \c{libhello}), it makes sense to create them \i{out of
+source tree}. Let's get to it:
+
+\
+$ cd ..
+$ mkdir hello2-gcc5-release
+$ ls -1F
+hello2/
+hello2-gcc5-release/
+
+$ b config.cxx=g++-5                             \
+  config.cc.coptions=-O3                         \
+  config.import.libhello=/tmp/hello-gcc5-release \
+  'configure(hello2/@hello2-gcc5-release/)'
+
+mkdir -p hello2-gcc5-release/build/
+save hello2-gcc5-release/build/config.build
+\
+
+Translated, \c{configure(hello2/@hello2-gcc5-release/)} means \i{\"configure
+the \c{hello2/} source directory in the \c{hello2-gcc5-release/} output
+directory\"}. In \c{build2} this \i{source directory} is called \c{src_root}
+and \i{output directory} \- \c{out_root}. Hm, we've already heard \c{out_root}
+mentioned somewhere before...
+
+Once the configuration is saved, we can develop our project without any
+annoyance:
+
+\
+$ b hello2-gcc5-release/
+c++ hello2/cxx{hello}
+ld hello2-gcc5-release/exe{hello}
+
+$ cd hello2-gcc5-release/
+
+$ b
+info: dir{./} is up to date
+
+$ b clean
+rm exe{hello}
+rm obje{hello}
+
+$ b -v
+g++-5 -I/tmp/hello-gcc5-release/libhello-1.0.0 -O3 -std=c++11 -o hello.o -c ../hello2/hello.cpp
+g++-5 -O3 -std=c++11 -o hello hello.o /tmp/hello-gcc5-release/libhello-1.0.0/hello/libhello-1.0.so
+\
+
+Some of you might have noticed that \c{hello2-gcc5-release/} and
+\c{/tmp/hello-gcc5-release/} look awfully similar and are now wondering if we
+could instead build \c{hello2} \i{inside} \c{/tmp/hello-gcc5-release/}? I am
+glad you've asked. In fact, we can just do:
+
+\
+$ cd ..
+$ ls -1F
+hello2/
+hello2-gcc5-release/
+
+$ b 'configure(hello2/@/tmp/hello-gcc5-release/hello2/)'
+mkdir -p /tmp/hello-gcc5-release/hello2/build/
+save /tmp/hello-gcc5-release/hello2/build/config.build
+
+$ b /tmp/hello-gcc5-release/hello2/
+c++ hello2/cxx{hello}@/tmp/hello-gcc5-release/hello2/
+ld /tmp/hello-gcc5-release/hello2/exe{hello}
+\
+
+Now that might seem like magic, but it's actually pretty logical. Why don't we
+need to specify any of the \c{config.c*} values this time? Because they are
+inherited from those specified for \c{/tmp/hello-gcc5-release} when we created
+the configuration with \c{bpkg create}. What about \c{config.import.libhello},
+don't we need at least that? Not really \- \c{libhello} will be found
+automatically since it is part of the same amalgamation.
+
+Of course, \c{bpkg} has no idea \c{hello2} is now part of its configuration:
+
+\
+$ bpkg status -d /tmp/hello-gcc5-release/ hello2
+unknown
+\
+
+This is what I meant when I said you can muck around in \c{bpkg}'s back yard as
+long as you understand the implications.
+
+But is there a way to make \c{bpkg} aware of our little project? You seem to
+really have all the right questions today. Actually, there is a very good
+reason why we would want that: if we upgrade \c{libhello} we would want
+\c{bpkg} to automatically reconfigure our project. As it is now, we will have
+to remember and do it ourselves.
+
+The only way to make \c{bpkg} aware of \c{hello2} is to turn it from merely a
+\c{build2} \i{project} into a \c{build2} \i{package}. While the topic of
+packaging is also for another time and place (the \c{build2} package manager
+manual), we can get away with something as simple as this:
+
+\
+$ cat >hello2/manifest
+: 1
+name: hello2
+version: 1.0.0
+summary: Improved \"Hello World\" program
+license: proprietary
+url: http://example.org/hello2
+email: hello2@example.org
+depends: libhello >= 1.0.0
+\
+
+For our purposes, the only really important value in this manifest is
+\c{depends} since it tells \c{bpkg} which package(s) we need. Let's give it a
+try. But first we will clean up our previous attempt at building \c{hello2}
+inside \c{/tmp/hello-gcc5-release/}:
+
+\
+$ b '{clean disfigure}(/tmp/hello-gcc5-release/hello2/)'
+rm /tmp/hello-gcc5-release/hello2/exe{hello}
+rm /tmp/hello-gcc5-release/hello2/obje{hello}
+rm /tmp/hello-gcc5-release/hello2/build/config.build
+rmdir /tmp/hello-gcc5-release/hello2/
+\
+
+Next, we use the \l{bpkg-pkg-build(1) \c{bpkg build}} command but instead of
+giving it a package name like we did before, we will point it to our \c{hello2}
+package directory (\c{bpkg} can fetch packages or it can build local package
+archives or package directories):
+
+\
+$ bpkg build -d /tmp/hello-gcc5-release/ ./hello2/
+  build hello2/1.0.0
+continue? [Y/n] y
+unpacked hello2/1.0.0
+configured hello2/1.0.0
+c++ hello2/cxx{hello}@/tmp/hello-gcc5-release/hello2-1.0.0/
+ld /tmp/hello-gcc5-release/hello2-1.0.0/exe{hello}
+updated hello2/1.0.0
+\
+
+Let's upgrade \c{libhello} and see what happens:
+
+\
+$ bpkg build -d /tmp/hello-gcc5-release/ -L libhello
+  build libformat/1.0.0 (required by libhello)
+  build libprint/1.0.0 (required by libhello)
+  upgrade libhello/1.1.0
+  reconfigure hello2 (dependent of libhello)
+continue? [Y/n] y
+disfigured hello2/1.0.0
+disfigured libhello/1.0.0
+[ ... fetching & unpacking ... ]
+configured libformat/1.0.0
+configured libprint/1.0.0
+configured libhello/1.1.0
+configured hello2/1.0.0
+[ ... updating libprint, libformat, and libhello ... ]
+updated libhello/1.1.0
+\
+
+As promised, \c{hello2} got reconfigured (it didn't get updated because of the
+\c{-L} option). We can now update it and give it a try:
+
+\
+$ bpkg update -d /tmp/hello-gcc5-release/ hello2
+c++ hello2/cxx{hello}@/tmp/hello-gcc5-release/hello2-1.0.0/
+ld /tmp/hello-gcc5-release/hello2-1.0.0/exe{hello}
+updated hello2/1.0.0
+
+$ /tmp/hello-gcc5-release/hello2-1.0.0/hello
+Hello, World!
+\
+
+To finish off, let's see how hard it will be to get a Clang build going:
+
+\
+$ cd /tmp
+$ mkdir hello-clang36-release
+$ cd hello-clang36-release
+
+$ bpkg create cc config.cxx=clang++-3.6 config.cc.coptions=-O3
+created new configuration in /tmp/hello-clang36-release/
+
+$ bpkg add https://build2.org/pkg/1/hello/testing
+added repository build2.org/hello/testing
+
+$ bpkg fetch
+fetching build2.org/hello/testing
+[... certificate authentication ...]
+fetching build2.org/hello/stable (complements build2.org/hello/testing)
+5 package(s) in 2 repository(s)
+
+$ bpkg build libhello/1.0.0 path/to/hello2/
+  build libhello/1.0.0
+  build hello2/1.0.0
+continue? [Y/n] y
+libhello-1.0.0.tar.gz        100% of 2428  B  983 kBps 00m01s
+fetched libhello/1.0.0
+unpacked libhello/1.0.0
+unpacked hello2/1.0.0
+configured libhello/1.0.0
+configured hello2/1.0.0
+c++ libhello-1.0.0/hello/cxx{hello}
+ld libhello-1.0.0/hello/liba{hello}
+c++ libhello-1.0.0/hello/cxx{hello}
+ld libhello-1.0.0/hello/libs{hello}
+c++ libhello-1.0.0/tests/test/cxx{driver}
+ld libhello-1.0.0/tests/test/exe{driver}
+c++ /path/to/hello2/cxx{hello}@hello2-1.0.0/
+ld hello2-1.0.0/exe{hello}
+updated libhello/1.0.0
+updated hello2/1.0.0
+\
+
+Are you still there? Ok, one last example. Let's see how hard it is to
+cross-compile.
+
+\
+$ mkdir hello-mingw64
+$ cd hello-mingw64
+
+$ bpkg create cc config.cxx=x86_64-w64-mingw32-g++
+created new configuration in /tmp/hello-mingw64/
+
+$ bpkg add https://build2.org/pkg/1/hello/stable
+added repository build2.org/hello/stable
+
+$ bpkg fetch
+fetching build2.org/hello/stable
+[... certificate authentication ...]
+2 package(s) in 1 repository(s)
+
+$ bpkg build -y hello
+libhello-1.0.0.tar.gz        100% of 2428  B  983 kBps 00m01s
+fetched libhello/1.0.0
+unpacked libhello/1.0.0
+hello-1.0.0.tar.gz           100% of 1057  B 6882 kBps 00m01s
+fetched hello/1.0.0
+unpacked hello/1.0.0
+configured libhello/1.0.0
+configured hello/1.0.0
+c++ hello-1.0.0/cxx{hello}
+c++ libhello-1.0.0/hello/cxx{hello}
+ld libhello-1.0.0/hello/libs{hello}
+ld hello-1.0.0/exe{hello}
+updated hello/1.0.0
+
+$ wine hello-1.0.0/hello.exe Windows
+Hello, Windows!
+\
+
+In fact, on a properly setup GNU/Linux machine (that automatically uses
+\c{wine} as an \c{.exe} interpreter) we can even run tests:
+
+\
+$ bpkg test libhello hello
+c++ libhello-1.0.0/tests/test/cxx{driver}
+ld libhello-1.0.0/tests/test/exe{driver}
+test libhello-1.0.0/tests/test/exe{driver}
+test hello-1.0.0/exe{hello}
+tested libhello/1.0.0
+tested hello/1.0.0
+\
+"
diff --git a/doc/intro2.cli b/doc/intro2.cli
deleted file mode 100644
index bb10b1d..0000000
--- a/doc/intro2.cli
+++ /dev/null
@@ -1,1390 +0,0 @@
-// file      : doc/intro2.cli
-// copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
-// license   : MIT; see accompanying LICENSE file
-
-"\name=build2-toolchain-intro"
-"\subject=toolchain"
-"\title=Toolchain Introduction"
-
-// TODO
-//
-// @@ refs to further docs
-//
-// STYLE
-//
-// @@ section boundary page breaks (
)
-// @@ when printed, code background is gone, but spaces still there
-//
-// PDF
-//
-// @@ tree output is garbled
-// @@ Could we use a nicer font, seeing that we embed them?
-//
-
-// NOTES
-//
-// - Maximum 
 line is 70 characters.
-//
-
-"
-\h1#tldr|TL;DR|
-
-\
-$ git clone ssh://example.org/hello.git
-$ tree hello
-hello/
-├── hello/
-│   ├── hello.cxx
-│   └── buildfile
-├── manifest
-└── repositories.manifest
-
-$ cd hello
-$ bdep init --config-create ../hello-gcc cc config.cxx=g++
-initializing project /tmp/hello/
-created configuration /tmp/hello-gcc/ (default, auto-synchronized)
-synchronizing:
-  new hello/0.1.0
-
-$ b
-c++ hello/cxx{hello}@../hello-gcc/hello/hello/
-ld ../hello-gcc/hello/hello/exe{hello}
-ln ../hello-gcc/hello/hello/exe{hello} -> hello/
-
-$ hello/hello World
-Hello, World!
-
-$ edit repositories.manifest   # add https://example.org/libhello.git
-$ edit manifest                # add 'depends: libhello ^1.0.0'
-$ edit hello/buildfile         # import libhello
-$ edit hello/hello.cxx         # use libhello
-
-$ b
-fetching from https://example.org/libhello.git
-synchronizing /tmp/hello-gcc/:
-  new libhello/1.0.0 (required by hello)
-  reconfigure hello/0.1.0
-c++ ../hello-gcc/libhello-1.0.0/libhello/cxx{hello}
-ld ../hello-gcc/libhello-1.0.0/libhello/libs{hello}
-c++ hello/cxx{hello}@../hello-gcc/hello/hello/
-ld ../hello-gcc/hello/hello/exe{hello}
-ln ../hello-gcc/hello/hello/exe{hello} -> hello/
-
-$ bdep fetch                   # refresh available versions
-$ bdep status -i               # review available versions
-hello configured 0.1.0
-  libhello ^1.0.0 configured 1.0.0 available [1.1.0]
-
-$ bdep sync libhello           # upgrade to latest
-synchronizing:
-  new libformat/1.0.0 (required by libhello)
-  new libprint/1.0.0 (required by libhello)
-  upgrade libhello/1.1.0
-  reconfigure hello/0.1.0
-
-$ bdep sync libhello/1.0.0     # downgrade
-synchronizing:
-  drop libprint/1.0.0 (unused)
-  drop libformat/1.0.0 (unused)
-  downgrade libhello/1.0.0
-  reconfigure hello/0.1.0
-\
-
-\h1#guide|Getting Started Guide|
-
-The aim of this guide is to get you started developing C/C++ projects with the
-\c{build2} toolchain. All the examples in this section include the relevant
-command output so if you just want to get a sense of what \c{build2} is about,
-then you don't have to install the toolchain and run the commands in order to
-follow along. If at the end you find \c{build2} appealing and would like to
-start using it or try the examples for yourself, you can jump straight to
-\l{build2-toolchain-install.xhtml The \c{build2} Toolchain Installation and
-Upgrade}.
-
-One of the primary goals of the \c{build2} toolchain is to provide a uniform
-interface across all the platforms and compilers. While the examples in this
-document assume a UNIX-like operation system, they will look pretty similar if
-you are on Windows. You just have to use appropriate paths, compilers, and
-options.
-
-The question we will try to answer in this section can be summarized as:
-
-\
-$ git clone .../hello.git && now-what?
-\
-
-That is, we clone an existing C/C++ project or would like to create a new one
-and then start hacking on it. We want to spend as little time and energy as
-possible on the initial and ongoing infrastructure maintenance: setting up
-build configurations, managing dependencies, continuous integration and
-testing, release management, etc. Or, as one C++ user aptly put it, \"\i{All I
-want to do is program.}\"
-
-\h#guide-hello|Hello, World|
-
-Let's see what programming with \c{build2} feels like by starting with a
-customary \i{\"Hello, World!\"} program (here we assume our current working
-directory is \c{/tmp}):
-
-\
-$ bdep new -t exe -l c++ hello
-created new executable project hello in /tmp/hello/
-\
-
-The \l{bdep-new(1)} command creates a \i{canonical} \c{build2} project. In
-our case it is an executable implemented in C++.
-
-\N|To create a library, pass \c{-t\ lib}. By default \c{new} also initializes
-a \c{git} repository and generates suitable \c{.gitignore} files (pass \c{-s\
-none} if you don't want that).|
-
-Let's take a look inside our new project:
-
-\
-$ tree hello
-hello/
-├── .git/
-├── .bdep/
-├── build/
-├── hello/
-│   ├── hello.cxx
-│   ├── buildfile
-│   └── testscript
-├── buildfile
-├── manifest
-└── repositories.manifest
-\
-
-\N|While the canonical project structure is strongly recommended, especially
-for new projects, \c{build2} is flexible enough to allow most commonly used
-arrangements.|
-
-Similar to version control tools, we normally run all \c{build2} tools from
-the project's source directory or one of its subdirectories, so:
-
-\
-$ cd hello
-\
-
-While the project layout is discussed in more detail in later sections, let's
-examine a couple of interesting files to get a sense of what's going on. We
-start with the source file which should look familiar:
-
-\
-$ cat hello/hello.cxx
-
-#include 
-
-using namespace std;
-
-int main (int argc, char* argv[])
-{
-  if (argc < 2)
-  {
-    cerr << \"error: missing name\" << endl;
-    return 1;
-  }
-
-  cout << \"Hello, \" << argv[1] << '!' << endl;
-}
-\
-
-\N|If you prefer the \c{.?pp} extensions over \c{.?xx} for your C++ source
-files, pass \c{-l\ c++,cpp} to the \c{new} command. See \l{bdep-new(1)} for
-details on this and other customization options.|
-
-Let's take a look at the accompanying \c{buildfile}:
-
-\
-$ cat hello/buildfile
-
-libs =
-#import libs += libhello%lib{hello}
-
-exe{hello}: {hxx ixx txx cxx}{*} $libs test{testscript}
-\
-
-As the name suggests, this file describes how to build things. While its
-content might look a bit cryptic, let's try to infer a couple of points
-without going into too much detail (the details are discussed in the following
-sections). That \c{exe{hello\}} on the left of \c{:} is a \i{target}
-(executable named \c{hello}) and what we have on the right are
-\i{prerequisites} (C++ source files, libraries, etc). This \c{buildfile} uses
-\l{b#name-patterns wildcard patterns} (that \c{*}) to automatically locate all
-the C++ source files. This means we don't have to edit our \c{buildfile} every
-time we add a source file to our project. There also appears to be some
-(commented out) infrastructure for importing and linking libraries (that
-\c{libs} variable). We will see how to use it in a moment. Finally, the
-\c{buildfile} also lists \c{testscript} as a prerequisite of \c{hello}. This
-file tests our target. Let's take a look inside:
-
-\
-$ cat hello/testscript
-
-: basics
-:
-$* 'World' >'Hello, World!'
-
-: missing-name
-:
-$* 2>>EOE != 0
-error: missing name
-EOE
-\
-
-Again, we are not going into detail here (see \l{testscript#intro Testscript
-Introduction} for a proper introduction), but to give you an idea, here we
-have two tests: the first (with id \c{basics}) verifies that our program
-prints the expected greeting while the second makes sure it handles the
-missing name error condition. Tests written in Testscript are concise,
-portable, and executed in parallel.
-
-Next up is \c{manifest}:
-
-\
-$ cat manifest
-: 1
-name: hello
-version: 0.1.0-a.0.z
-summary: hello executable project
-license: proprietary
-url: https://example.org/hello
-email: you@example.org
-#depends: libhello ^1.0.0
-\
-
-The \c{manifest} file is what makes a build system project a \i{package}. It
-contains all the metadata that a user of a package might need to know: its
-name, version, license, dependencies, etc., all in one place.
-
-\N|Refer to \l{bpkg#manifest-format Manifest Format} for the general format of
-\c{build2} manifest files and to \l{bpkg#manifest-package Package Manifest}
-for details on the package manifest values.|
-
-As you can see, \c{manifest} created by \l{bdep-new(1)} contains some dummy
-values which you would want to adjust before publishing your package. But
-let's resist the urge to adjust that strange looking \c{0.1.0-a.0.z} until we
-discuss package versioning.
-
-\N|Next to \c{manifest} you might have noticed the \c{repositories.manifest}
-file \- we will discuss its function later, when we talk about dependencies
-and where they come from.|
-
-Project in hand, let's build it. Unlike other programming languages, C++
-development usually involves juggling a handful of build configurations:
-several compilers and/or targets (\c{build2} is big on cross-compiling),
-debug/release, different sanitizers and/or static analysis tools, and so
-on. As a result, \c{build2} is optimized for multi-configuration
-usage. However, as we will see shortly, one build configuration can be
-designated as the default with additional conveniences.
-
-The \l{bdep-init(1)} command is used to initialize a project in a build
-configuration. As a shortcut, it can also create a new build configuration in
-the process, which is just what we need here. Let's start with GCC (remember
-we are in the project's root directory):
-
-\
-$ bdep init -C ../hello-gcc @gcc cc config.cxx=g++
-initializing project /tmp/hello/
-created configuration @gcc /tmp/hello-gcc/ (default, auto-synchronized)
-synchronizing:
-  new hello/0.1.0-a.0.19700101000000
-\
-
-The \cb{--create|-C} option instructs \c{init} to create a new configuration
-in the specified directory (\c{../hello-gcc} in our case). To make referring
-to configurations easier, we can give it a name, which is what we do with
-\c{@gcc}. The next argument (\c{cc}, stands for \i{C-common}) is the build
-system module we would like to configure. It implements compilation and
-linking rules for the C and C++ languages. Finally, \c{config.cxx=g++} is (one
-of) this module's configuration variables that specifies the C++ compiler we
-would like to use (the corresponding C compiler will be determined
-automatically). Let's for now also ignore that \c{synchronizing:...} bit along
-with strange-looking \c{19700101000000} in the version \- it will become clear
-what's going on here in a moment.
-
-Now the same for Clang:
-
-\
-$ bdep init -C ../hello-clang @clang cc config.cxx=clang++
-initializing project /tmp/hello/
-created configuration @clang /tmp/hello-clang/ (auto-synchronized)
-synchronizing:
-  new hello/0.1.0-a.0.19700101000000
-\
-
-If we check the parent directory, we should now see two build configurations
-next to our project:
-
-\
-$ ls ..
-hello/
-hello-gcc/
-hello-clang/
-\
-
-Things will also look pretty similar if you are on Windows instead of a
-UNIX-like operating system. For example, to initialize our project on Windows
-with Visual Studio, start the Visual Studio development command prompt and
-then run:
-
-\N|Currently we have to run \c{build2} tools from a suitable Visual Studio
-development command prompt. This requirement will likely be removed in the
-future.|
-
-\
-> bdep init -C ..\hello-debug @debug cc     ^
-  config.cxx=cl                             ^
-  \"config.cc.coptions=/MDd /Z7\"             ^
-  config.cc.loptions=/DEBUG
-
-> bdep init -C ..\hello-release @release cc ^
-  config.cxx=cl                             ^
-  config.cc.coptions=/O2
-\
-
-\N|Besides the \c{coptions} (compile options) and \c{loptions} (link options),
-other commonly used \c{cc} module configuration variables are \c{poptions}
-(preprocess options) and \c{libs} (extra libraries to link). We can also use
-their \c{config.c.*} (C compilation) and \c{config.cxx.*} (C++ compilation)
-variants if we only want them applied during the respective language
-compilation. For example:
-
-\
-$ bdep init ... cc       \
-  config.cxx=clang++     \
-  config.cc.coptions=-g  \
-  config.cxx.coptions=-stdlib=libc++
-\
-
-|
-
-One difference you might have noticed when creating the \c{gcc} and \c{clang}
-configurations above is that the first one was designated as the default. The
-default configuration is used by \c{bdep} commands if no configuration is
-specified explicitly (see \l{bdep-projects-configs(1)} for details). It is
-also the configuration that is used if we run the build system in the
-project's source directory. So, normally, you would make your every day
-development configuration the default. Let's try that:
-
-\
-$ bdep status
-hello configured 0.1.0-a.0.19700101000000
-
-$ b
-c++ hello/cxx{hello}@../hello-gcc/hello/hello/
-ld ../hello-gcc/hello/hello/exe{hello}
-ln ../hello-gcc/hello/hello/exe{hello} -> hello/
-
-$ b test
-test hello/test{testscript} ../hello-gcc/hello/hello/exe{hello}
-
-$ hello/hello World
-Hello, World!
-\
-
-In contrast, the Clang configuration has to be requested explicitly:
-
-\
-$ bdep status @clang
-hello configured 0.1.0-a.0.19700101000000
-
-$ b ../hello-clang/hello/
-c++ hello/cxx{hello}@../hello-clang/hello/hello/
-ld ../hello-clang/hello/hello/exe{hello}
-
-$ b test: ../hello-clang/hello/
-test hello/test{testscript} ../hello-clang/hello/hello/exe{hello}
-
-$ ../hello-clang/hello/hello/hello World
-Hello, World!
-\
-
-\N|To see the actual compilation command lines, run \c{b\ -v} and for even
-more details, run \c{b\ -V}. See \l{b(1)} for more information on these
-and other build system options.|
-
-While we are here, let's also check how hard it would be to cross-compile:
-
-\
-$ bdep init -C ../hello-mingw @mingw cc config.cxx=x86_64-w64-mingw32-g++
-initializing project /tmp/hello/
-created configuration @mingw /tmp/hello-mingw/ (auto-synchronized)
-synchronizing:
-  new hello/0.1.0-a.0.19700101000000
-
-$ b ../hello-mingw/hello/
-c++ hello/cxx{hello}@../hello-mingw/hello/hello/
-ld ../hello-mingw/hello/hello/exe{hello}
-\
-
-As you can see, cross-compiling in \c{build2} is nothing special. In our case,
-on a properly setup GNU/Linux machine (that automatically uses \c{wine} as an
-\c{.exe} interpreter) we can even run tests (in \c{build2} this is called
-\i{cross-testing}):
-
-\
-$ b test: ../hello-mingw/hello/
-test hello/test{testscript} ../hello-mingw/hello/hello/exe{hello}
-
-$ ../hello-mingw/hello/hello/hello.exe Windows
-Hello, Windows!
-\
-
-Let's review what it takes to initialize a project's infrastructure and
-perform the first build. For an existing project:
-
-\
-$ git clone .../hello.git
-$ cd hello
-$ bdep init -C ../hello-gcc @gcc cc config.cxx=g++
-$ b
-\
-
-For a new project:
-
-\
-$ bdep new -t exe -l c++ hello
-$ cd hello
-$ bdep init -C ../hello-gcc @gcc cc config.cxx=g++
-$ b
-\
-
-If you prefer, the \c{new} and \c{init} steps can be combined into a single
-command:
-
-\
-$ bdep new -t exe -l c++ hello -C hello-gcc @gcc cc config.cxx=g++
-\
-
-Now is also a good time to get an overview of the \c{build2} toolchain. After
-all, we have already used two of its tools (\c{bdep} and \c{b}) without a
-clear understanding of what they actually are.
-
-Unlike most other programming languages that encapsulate the build system,
-package dependency manager, and project dependency manager into a single tool
-(such as Rust's \c{cargo} or Go's \c{go}), \c{build2} is a hierarchy of
-several tools that you will be using directly and which together with your
-version control system (VCS) will constitute the core of your project
-management toolset.
-
-\N|While \c{build2} can work without a VCS, this will result in reduced
-functionality.|
-
-At the bottom of the hierarchy is the build system, \l{b(1)}. Next comes the
-package dependency manager, \l{bpkg(1)}. It is primarily used for \i{package
-consumption} and depends on the build system. The top of the hierarchy is the
-project dependency manager, \l{bdep(1)}. It is used for \i{project
-development} and relies on \c{bpkg} for building project packages and their
-dependencies.
-
-\N|The main reason for this separation is modularity and the resulting
-flexibility: there are situations where we only need the build system (for
-example, when building a package for a system package manager where all the
-dependencies should be satisfied from the system repository), or only the
-build system and package manager (for example, when a build bot is building a
-package for testing).
-
-Note also that strictly speaking \c{build2} is not C/C++-specific; its build
-model is general enough to handle any DAG-based operations and its
-package/project dependency management can be used for any compiled language.|
-
-\N|As we will see in a moment, \c{build2} also integrates with your VCS in
-order to automate project versioning. Note that currently only \c{git(1)} is
-supported.|
-
-Let's now move on to the reason why there is \i{dep} in the \c{bdep} name:
-dependency management.
-
-
-\h#guide-repositories|Package Repositories|
-
-Say we have realized that writing \i{\"Hello, World!\"} programs is a fairly
-common task and that someone must have written a library to help with that. So
-let's see if we can find something suitable to use in our project.
-
-Where should we look? That's a good question. But before we can try to answer
-it, we need to understand where \c{build2} can source dependencies. In
-\c{build2} packages come from \i{package repositories}. Two commonly used
-repository types are \i{version control} and \i{archive}-based (see
-\l{bpkg-repository-types(1)} for details).
-
-As the name suggests, a version control-based repository uses a VCS as its
-distribution mechanism. \N{Currently, only \c{git} is supported.} Such a
-repository normally contains multiple versions of a single package or,
-perhaps, of a few related packages.
-
-An archive-based repository contains multiple, potentially unrelated
-packages/versions as archives along with some meta information (package list,
-prerequisite/complement repositories, signatures, etc) that are all accessible
-via HTTP(S).
-
-Version control and archive-based repositories have different
-trade-offs. Version control-based repositories are great for package
-developers: With services like GitHub they are trivial to setup. In fact, your
-project's (already existing) VCS repository will normally be the \c{build2}
-package repository \- you might need to add a few files, but that's about it.
-
-However, version control-based repositories are not without drawbacks: It will
-be hard for your users to discover your packages (try searching for \"hello
-library\" on GitHub \- most of the results are not even in C++ let alone
-packaged for \c{build2}). There is also the issue of continuous availability:
-users can delete their repositories, services may change their policies or go
-out of business, and so on. Version control-based repositories also lack
-repository authentication and package signing. Finally, obtaining the
-available package list for such repositories can be slow.
-
-A central, archive-based repository would address all these drawbacks: It
-would be a single place to search for packages. Published packages will never
-disappear and can be easily mirrored. Packages are signed and the repository
-is authenticated (see \l{bpkg-repository-signing(1)} for details). And, last,
-but not least, archive-based repositories are fast.
-
-\l{https://cppget.org cppget.org} is the \c{build2} community's central
-package repository (which we hope one day will become \i{the C++ package
-repository}). As an added benefit, packages on \l{https://cppget.org
-cppget.org} are continuously \l{https://cppget.org/?builds built and tested} on
-all the major platform/compiler combinations with the results available as
-part of the package description.
-
-\N|The main drawback of archive-based repositories is the setup cost. Getting
-a basic repository going is relatively easy \- all you need is an HTTP(S)
-server. Adding a repository web interface like that on \l{https://cppget.org
-cppget.org} will require running \l{https://cppget.org/brep \c{brep}}. And
-adding CI will require running a bunch of build bots
-(\l{https://cppget.org/bbot \c{bbot}}).|
-
-\N|CI support for version control-based repositories is a work in progress.|
-
-To summarize, version control-based repositories are great for package
-developers while a central, archive-based repository is convenient for package
-consumers. A reasonable strategy is then for package developers to publish
-their releases to a central repository. Package consumers can then decide
-which repository to use based on their needs. For example, one could use
-\l{https://cppget.org cppget.org} as a (fast, reliable, and secure) source of
-stable versions but also add, say, \c{git} repositories for select packages
-(perhaps with the \c{#HEAD} fragment filter to improve download speed) for
-testing development snapshots. In this model the two repository types
-complement each other.
-
-\N|Support for automated publishing of tagged releases to an archive-based
-repository is a work in progress.|
-
-Let's see how all this works in practice. Go over to \l{https://cppget.org
-cppget.org} and type \"hello library\" in the search box. At the top of the
-search result you should see the \l{https://cppget.org/libhello \c{libhello}}
-package and if you follow the link you will see the package description page
-along with a list of available versions. Pick a version that you like and you
-will see the package version description page with quite a bit of information,
-including the list of platform/compiler combinations that this version has
-been successfully (or unsuccessfully) tested with. If you like what you see,
-copy the \c{location} value \- this is the repository location where this
-package version can be sourced from.
-
-\N|The \l{https://cppget.org cppget.org} repository is split into several
-sections: \c{stable}, \c{testing}, \c{beta}, \c{alpha} and \c{legacy}, with
-each section having its own repository location (see the repository's
-\l{https://cppget.org/?about about} page for details on each section's
-policies). Note also that \c{testing} is complemented by \c{stable}, \c{beta}
-by \c{testing}, and so on, so you only need to choose the lowest stability
-level and you will automatically \"see\" packages from the more stable
-sections.|
-
-\N|The \l{https://cppget.org cppget.org} \c{stable} sections will always
-contain the \c{libhello} library version \c{1.0.X} that was generated using
-the following \l{bdep-new(1)} command line:
-
-\
-$ bdep new -t lib -l c++ libhello
-\
-
-It can be used as a predictable test dependency when setting up new projects.|
-
-Let's say we've visited the \c{libhello} project's
-\l{https://git.build2.org/cgit/hello/libhello/ home page} (for example by
-following a link from the package details page) and noticed that it is being
-developed in a \c{git} repository. How can we see what's available there? If
-the releases are tagged, then we can infer the available released versions
-from the tags. But that doesn't tell us anything about what's happening on the
-\c{HEAD} or in the branches. For that we can use the package manager's
-\l{bpkg-rep-info(1)} command:
-
-\
-$ bpkg rep-info https://git.build2.org/hello/libhello.git
-libhello/1.0.0
-libhello/1.1.0
-\
-
-As you can see, besides \c{1.0.0} that we have seen on \c{cppget.org/stable},
-there is also \c{1.1.0} (which is perhaps being tested in
-\c{cppget.org/testing}). We can also check what might be available on the
-\c{HEAD} (see \l{bpkg-repository-types(1)} for details on the \c{git}
-repository URL format):
-
-\
-$ bpkg rep-info https://git.build2.org/hello/libhello.git#HEAD
-libhello/1.1.1-a.0.20180504111511.2e82f7378519
-\
-
-\N|We can also use the \c{rep-info} command on archive-based repositories,
-however, if available, the web interface is usually more convenient and
-provides more information.|
-
-To summarize, we found two repositories for the \c{libhello} package: the
-archive-based \l{https://cppget.org cppget.org} that contains the released
-versions as well as its development \c{git} repository where we can get the
-bleeding edge stuff. Let's now see how we can add \c{libhello} to our
-project.
-
-
-\h#guide-add-remove-deps|Adding and Removing Dependencies|
-
-So we found \c{libhello} that we would like to use in our \c{hello}
-project. First, we edit the \c{repositories.manifest} file found in the root
-directory of our project and add one of the \c{libhello} repositories as a
-prerequisite. Let's start with \l{https://cppget.org cppget.org}:
-
-\
-role: prerequisite
-location: https://pkg.cppget.org/1/stable
-\
-
-\N|Refer to \l{bpkg#manifest-repository Repository Manifest} for details on
-the repository manifest values.|
-
-Next, we edit the \c{manifest} file (again, found in the root of our project)
-and specify the dependency on \c{libhello} with optional version constraint.
-For example:
-
-\
-depends: libhello ^1.0.0
-\
-
-Let's briefly discuss version constraints (for details see the
-\l{bpkg#manifest-package-depends \c{depends}} value documentation). A version
-constraint can be expressed with a comparison operator (\c{==}, \c{>},
-\c{<}, \c{>=}, \c{<=}), a range shortcut operator (\c{~} and \c{^}), or a
-range. Here are a few examples:
-
-\
-depends: libhello == 1.2.3
-depends: libhello >= 1.2.3
-
-depends: libhello ~1.2.3
-depends: libhello ^1.2.3
-
-depends: libhello [1.2.3 1.2.9)
-\
-
-You may already be familiar with the tilde (\c{~}) and caret (\c{^})
-constraints from dependency managers for other languages. To recap, tilde
-allows upgrades to any further patch versions while caret also allows upgrades
-to further minor versions. They are equivalent to the following ranges:
-
-\
-~X.Y.Z  [X.Y.Z  X.Y+1.0)
-
-^X.Y.Z  [X.Y.Z  X+1.0.0)  if X >  0
-^0.Y.Z  [0.Y.Z  0.Y+1.0)  if X == 0
-\
-
-\N|Zero major version component is customarily used during early development
-where the minor version effectively becomes major. As a result, the tilde
-constraint has a special treatment of this case.|
-
-Unless you have good reasons not to (for example, a dependency does not use
-semantic versioning), we suggest that you use the \c{^} constraint which
-provides a good balance between compatibility and upgradability with \c{~}
-being a more conservative option.
-
-Ok, we've specified where our package comes from (\c{repositories.manifest})
-and which versions we find acceptable (\c{manifest}). The next step is to edit
-\c{hello/buildfile} and import the \c{libhello} library into our build:
-
-\
-import libs += libhello%lib{hello}
-\
-
-Finally, we modify our source code to use the library:
-
-\
-#include 
-...
-
-int main (int argc, char* argv[])
-{
-  ...
-  hello::say_hello (cout, argv[1]);
-}
-\
-
-\N|You are probably wondering why we have to specify this repeating
-information in so many places. Let's start with the source code: we can't
-specify the version constraint or location there because it will have to be
-repeated in every source file that uses the dependency.
-
-Moving up, \c{buildfile} is also not a good place to specify this information
-for the same reason (a library can be imported in multiple buildfiles) plus
-the build system doesn't really know anything about version constraints or
-repositories which is the purview of the dependency management tools.
-
-Finally, we have to separate the version constraint and the location because
-the same package can be present in multiple repositories with different
-policies. For example, when a package from a version control-based repository
-is published in an archive-based repository, its \c{repositories.manifest}
-file is ignored and all its dependencies should be available from the
-archive-based repository itself (or its fixed set of prerequisite
-repositories). In other words, \c{manifest} belongs to a package while
-\c{repositories.manifest} \- to a repository.
-
-Also note that this is unlikely to become burdensome since adding new
-dependencies is not something that happens often. There are also plans to
-automate this with a \c{bdep-add(1)} command in the future.|
-
-To summarize, these are the files we had to modify to add a dependency
-to our project:
-
-\
-repositories.manifest   # add https://pkg.cppget.org/1/stable
-manifest                # add 'depends: libhello ^1.0.0'
-buildfile               # import libhello
-hello.cxx               # use libhello
-\
-
-With a new dependency added, let's check the status of our project:
-
-\
-$ bdep status
-fetching pkg:cppget.org/stable (prerequisite of dir:/tmp/hello)
-warning: authenticity of the certificate for pkg:cppget.org/stable
-         cannot be established
-certificate is for cppget.org, \"Code Synthesis\" 
-certificate SHA256 fingerprint:
-86:BA:D4:DE:2C:87:1A:EE:38:<...>:5A:EA:F4:F7:8C:1D:63:30:C6
-trust this certificate? [y/n] y
-
-hello configured 0.1.0-a.0.19700101000000
-      available  0.1.0-a.0.19700101000000#1
-\
-
-The \l{bdep-status(1)} command has detected that the dependency information
-has changed and tells us that a new \i{iteration} of our project (that \c{#1})
-is now available for \i{synchronization} with the build configuration.
-
-We've also been prompted to authenticate the prerequisite repository. This
-will have to happen once for every build configuration we initialize our
-project in and can quickly become tedious. To overcome this, we can mention
-the certificate fingerprint that we wish to automatically trust in the
-\c{repositories.manifest} file (replace it with the actual fingerprint from
-the repository's about page):
-
-\
-role: prerequisite
-location: https://pkg.cppget.org/1/stable
-trust: 86:BA:D4:DE:2C:87:1A:EE:38:<...>:5A:EA:F4:F7:8C:1D:63:30:C6
-\
-
-To synchronize a project with one or more build configurations we use the
-\l{bdep-sync(1)} command:
-
-\
-$ bdep sync
-synchronizing:
-  new libhello/1.0.0 (required by hello)
-  upgrade hello/0.1.0-a.0.19700101000000#1
-\
-
-Or we could just build the project without an explicit \c{sync} \- if
-necessary, it will be automatically synchronized:
-
-\
-$ b
-synchronizing:
-  new libhello/1.0.0 (required by hello)
-  upgrade hello/0.1.0-a.0.19700101000000#1
-c++ ../hello-gcc/libhello-1.0.0/libhello/cxx{hello}
-ld ../hello-gcc/libhello-1.0.0/libhello/libs{hello}
-c++ hello/cxx{hello}@../hello-gcc/hello/hello/
-ld ../hello-gcc/hello/hello/exe{hello}
-ln ../hello-gcc/hello/hello/exe{hello} -> hello/
-\
-
-The synchronization as performed by the \c{sync} command is two-way:
-dependency packages are first added, removed, upgraded, or downgraded in build
-configurations according to the project's version constraints and user
-input. Then the actual versions of the dependencies present in the build
-configurations are recorded in the project's \c{lockfile} so that if desired,
-the build can be reproduced exactly. \N{The \c{lockfile} functionality is not
-yet implemented.} For a new dependency the latest available version that
-satisfies the version constraint is used.
-
-\N|Synchronization is also the last step in the \l{bdep-init(1)} command's
-logic.|
-
-Let's now examine the status in all (\c{--all|-a}) the build configurations
-and include the immediate dependencies (\c{--immediate|-i}):
-
-\
-$ bdep status -ai
-in configuration @gcc:
-hello configured 0.1.0-a.0.19700101000000#1
-  libhello ^1.0.0 configured 1.0.0
-
-in configuration @clang:
-hello configured 0.1.0-a.0.19700101000000
-      available 0.1.0-a.0.19700101000000#1
-\
-
-Since we didn't specify a configuration explicitly, only the default (\c{gcc})
-was synchronized. Normally, you would try a new dependency in one
-configuration, make sure everything looks good, then synchronize the rest with
-\c{--all|-a} (or, again, just build what you need directly). Here are a few
-examples (see \l{bdep-projects-configs(1)} for details):
-
-\
-$ bdep sync -a
-$ bdep sync @gcc @clang
-$ bdep sync -c ../hello-mingw
-\
-
-To get rid of a dependency, we simply remove it from the \c{manifest} file
-and synchronize the project. For example, assuming \c{libhello} is no longer
-mentioned as a dependency in our \c{manifests}:
-
-\
-$ bdep status
-hello configured 0.1.0-a.0.19700101000000#1
-      available  0.1.0-a.0.19700101000000#2
-
-$ bdep sync
-synchronizing:
-  drop libhello/1.0.0 (unused)
-  upgrade hello/0.1.0-a.0.19700101000000#2
-\
-
-
-\h#guide-upgrade-downgrade-deps|Upgrading and Downgrading Dependencies|
-
-Let's say we would like to try that \c{1.1.0} version we have seen in
-the \c{libhello} \c{git} repository. First, we need to add the
-repository to the \c{repositories.manifest} file:
-
-\
-role: prerequisite
-location: https://git.build2.org/hello/libhello.git
-\
-
-\N|Note that we don't need the \c{trust} value since \c{git} repositories
-are not authenticated.|
-
-To refresh the list of available dependency versions we use the
-\l{bdep-fetch(1)} command (or the \c{--fetch|-f} option to \c{status}):
-
-\
-$ bdep fetch
-$ bdep status libhello
-libhello configured 1.0.0 available [1.1.0]
-\
-
-To upgrade (or downgrade) dependencies we again use the \l{bdep-sync(1)}
-command. We can upgrade one or more specific dependencies by listing them
-as arguments to \c{sync}:
-
-\
-$ bdep sync libhello
-synchronizing:
-  new libformat/1.0.0 (required by libhello)
-  new libprint/1.0.0 (required by libhello)
-  upgrade libhello/1.1.0
-  upgrade hello/0.1.0-a.0.19700101000000#3
-\
-
-Without an explicit version or the \c{--patch|-p} option, \c{sync} will
-upgrade the specified dependencies to the latest available versions. For
-example, if we don't like version \c{1.1.0}, we can downgrade it back to
-\c{1.0.0} by specifying the version explicitly (we pass \c{--old-available|-o}
-to \c{status} to see the old versions):
-
-\
-$ bdep status -o libhello
-libhello configured 1.1.0 available (1.1.0) [1.0.0]
-
-$ bdep sync libhello/1.0.0
-synchronizing:
-  drop libprint/1.0.0 (unused)
-  drop libformat/1.0.0 (unused)
-  downgrade libhello/1.0.0
-  reconfigure hello/0.1.0-a.0.19700101000000#3
-\
-
-\N|The available versions are listed in the descending order with \c{[]}
-indicating that the version is only available as a dependency and \c{()}
-marking the current version.|
-
-Instead of specific dependencies we can also upgrade (\c{--upgrade|-u}) or
-patch (\c{--patch|-p}) immediate (\c{--immediate|-i}) or all
-(\c{--recursive|-r}) dependencies of our project.
-
-As a more realistic example, version \c{1.1.0} of \c{libhello} depends on two
-other libraries: \c{libformat} and \c{libprint}. Here is our project's
-dependency tree while we were still using that version:
-
-\
-$ bdep status -r
-hello configured 0.1.0-a.0.19700101000000#3
-  libhello ^1.0.0 configured 1.1.0
-    libformat ^1.0.0 configured 1.0.0
-    libprint ^1.0.0 configured 1.0.0
-\
-
-A typical conservative dependency management workflow would look like this:
-
-\
-$ bdep status -fi  # refresh and examine immediate dependencies
-hello configured 0.1.0-a.0.19700101000000#3
-  libhello configured 1.1.0 available [2.0.0] [1.2.0] [1.1.2] [1.1.1]
-
-$ bdep sync -pi    # upgrade immediate to latest patch version
-synchronizing:
-  upgrade libhello/1.1.2
-  reconfigure hello/0.1.0-a.0.19700101000000#3
-continue? [Y/n] y
-\
-
-Notice that in case of such mass upgrades you are prompted for confirmation
-before anything is actually changed (unless you pass \c{--yes|-y}).
-
-In contrast, the following would be a fairly aggressive workflow where we
-upgrade everything to the latest available version (version constraints
-permitting; here we assume \c{^1.0.0} was used for all the dependencies):
-
-\
-$ bdep status -fr  # refresh and examine all dependencies
-hello configured 0.1.0-a.0.19700101000000#3
-  libhello configured 1.1.0 available [2.0.0] [1.2.0] [1.1.1]
-    libprint configured 1.0.0 available [2.0.0] [1.1.0] [1.0.1]
-    libformat configured 1.0.0 available [2.0.0] [1.1.0] [1.0.1]
-
-$ bdep sync -ur    # upgrade all to latest available version
-synchronizing:
-  upgrade libprint/1.1.0
-  upgrade libformat/1.1.0
-  upgrade libhello/1.2.0
-  reconfigure hello/0.1.0-a.0.19700101000000#3
-continue? [Y/n] y
-\
-
-We can also have something in between: patch all (\c{sync\ -pr}), upgrade
-immediate (\c{sync\ -ui}), or even upgrade immediate and patch the rest
-(\c{sync\ -ui} followed by \c{sync\ -pr}).
-
-
-\h#guide-versioning-releasing|Versioning and Release Management|
-
-Let's now discuss versioning and release management and, yes, that
-strange-looking \c{0.1.0-a.0.19700101000000} we keep seeing. While a build
-system project doesn't need a version and a \c{bpkg} package can use custom
-versioning schemes (see \l{bpkg#package-version Package Version}), a project
-managed by \c{bdep} must use \i{standard versioning}. \N{A dependency, which
-is a \c{bpkg} package, need not use standard versioning.}
-
-Standard versioning (\i{stdver}) is a \l{https://semver.org semantic
-versioning} (\i{semver}) scheme with a more precisely defined pre-release
-component and without any build metadata.
-
-\N|If you believe that \i{semver} is just \c{\i{major}.\i{minor}.\i{patch}},
-then in your worldview \i{stdver} would be the same as \i{semver}. In reality,
-\i{semver} also allows loosely defined pre-release and build metadata
-components. For example, \c{1.2.3-beta.1+build.23456} is a valid \i{semver}.|
-
-A standard version has the following form:
-
-\c{\i{major}\b{.}\i{minor}\b{.}\i{patch}[\b{-}\i{prerel}]}
-
-The \ci{major}, \ci{minor}, and \ci{patch} components have the same meaning as
-in \i{semver}. The \ci{prerel} component is used to provide \i{continuous
-versioning} of our project between releases. Specifically, during development
-of a new version we may want to publish several pre-releases, for example,
-alpha or beta. In between those we may also want to publish a number of
-snapshots, for example, for CI. With continuous versioning all these releases,
-pre-releases, and snapshots are assigned unique, properly ordered versions.
-
-\N|Continuous versioning is a cornerstone of the \c{build2} project dependency
-management. In case of snapshots, an appropriate version is assigned
-automatically in cooperation with your VCS.|
-
-The \ci{prerel} component for a pre-release has the following form:
-
-\c{(\b{a}|\b{b})\b{.}\i{num}}
-
-Here \cb{a} stands for alpha, \cb{b} stands for beta, and \ci{num} is the
-alpha/beta number. For example:
-
-\
-1.1.0        # final              release  for 1.1.0
-1.2.0-a.1    # first  alpha   pre-release  for 1.2.0
-1.2.0-a.2    # second alpha   pre-release  for 1.2.0
-1.2.0-b.1    # first  beta    pre-release  for 1.2.0
-1.2.0        # final              release  for 1.2.0
-\
-
-The \ci{prerel} component for a snapshot has the following form:
-
-\c{(\b{a}|\b{b})\b{.}\i{num}\b{.}\i{snapsn}[\b{.}\i{snapid}]}
-
-Where \ci{snapsn} is the snapshot sequence number and \ci{snapid} is
-the snapshot id. In case of \c{git}, \ci{snapsn} is the commit timestamp
-in the \c{YYYYMMDDhhmmss} form and UTC timezone while \ci{snapid} is
-a 12-character abbreviated commit id. For example:
-
-\
-1.2.3-a.1.20180319215815.26efe301f4a7
-\
-
-Notice also that a snapshot version is ordered \i{after} the corresponding
-pre-release version. That is, \c{1.2.3-a.1\ <\ 1.2.3-a.1.1}. As a result, it
-is customary to start the development of a new version with \c{X.Y.Z-a.0.z},
-that is, a snapshot after the (non-existent) zero'th alpha release. \N{We will
-explain the meaning of \cb{z} in this version momentarily.} The following
-chronologically-ordered versions illustrate a typical release flow of a
-project that uses \c{git} as its VCS:
-
-\
-0.1.0-a.0.19700101000000               # snapshot (no commits yet)
-0.1.0-a.0.20180319215815.26efe301f4a7  # snapshot (first commit)
-...                                    # more commits/snapshots
-0.1.0-a.1                              # pre-release (first alpha)
-0.1.0-a.1.20180319221826.a6f0f41205b8  # snapshot
-...                                    # more commits/snapshots
-0.1.0-a.2                              # pre-release (second alpha)
-0.1.0-a.2.20180319231937.b701052316c9  # snapshot
-...                                    # more commits/snapshots
-0.1.0-b.1                              # pre-release (first beta)
-0.1.0-b.1.20180319242038.c812163417da  # snapshot
-...                                    # more commits/snapshots
-0.1.0                                  # release
-0.2.0-a.0.20180319252139.d923274528eb  # snapshot (first in 0.2.0)
-...
-\
-
-For a more detailed discussion of standard versioning and its support in
-\c{build2} refer to \l{b#module-version Version Module}.
-
-Let's now see how this works in practice by publishing a couple of versions
-for our \c{hello} project. By now it should be clear what that
-\c{0.1.0-a.0.19700101000000} means \- it is the first snapshot version of our
-project. Since there are no commits yet, it has the UNIX epoch as its commit
-timestamp. As the first step, let's try to commit our project and see what
-changes:
-
-\
-$ git add .
-$ git commit -m \"Start hello project\"
-
-$ bdep status
-hello configured 0.1.0-a.0.19700101000000
-      available  0.1.0-a.0.20180507062614.ee006880fc7e
-\
-
-Just like with changes to dependency information, \c{status} has detected that
-a new (snapshot) version of our project is available for synchronization.
-
-\N|Another way to view the project's version (which works even if we are
-not using \c{bdep}) is with the build system's \c{info} operation:
-
-\
-$ b info
-project: hello
-version: 0.1.0-a.0.20180507062614.ee006880fc7e
-summary: hello executable project
-...
-\
-
-|
-
-Let's synchronize with the default build configuration:
-
-\
-$ bdep sync
-synchronizing:
-  upgrade hello/0.1.0-a.0.20180507062614.ee006880fc7e
-
-$ bdep status
-hello configured 0.1.0-a.0.20180507062614.ee006880fc7e
-\
-
-\N|Notice that we didn't have to manually change the version anywhere. All we
-had to do was commit our changes and a new snapshot version was automatically
-derived by \c{build2} from the new \c{git} commit. Without this automation
-continuous versioning would hardly be practical.|
-
-If we now make another commit, we will see a similar picture:
-
-\
-$ bdep status
-hello configured 0.1.0-a.0.20180507062614.ee006880fc7e
-      available  0.1.0-a.0.20180507062615.8fb9de05b38f
-\
-
-\N|Note that you don't need to manually run \c{sync} after every commit. As
-discussed earlier, you can simply run the build system to update your project
-and things will get automatically synchronized if necessary.|
-
-Ok, time for our first release. Let's start with \c{0.1.0-a.1}. Unlike
-snapshots, for pre-releases as well as final releases we have to update the
-version in the \c{manifest} file manually:
-
-\
-version: 0.1.0-a.1
-\
-
-\N|The \c{manifest} file is the singular place where we specify the package
-version. The build system's \l{b#module-version \c{version} module} makes it
-available in various forms in buildfiles and even source code.|
-
-To ensure continuous versioning, this change to version must be the last commit
-for this (pre-)release which itself must be immediately followed by a second
-change to the version starting the development of the next (pre-)release. We
-also recommend that you tag the release commit with a tag name in the
-\c{\b{v}\i{X}.\i{Y}.\i{Z}} form.
-
-\N|Having regular release tag names with the \cb{v} prefix allows one to
-distinguish them from other tags, for example, with wildcard patterns.|
-
-Here is the release workflow for our example:
-
-\
-$ git commit -a -m \"Release version 0.1.0-a.1\"
-$ git tag -a v0.1.0-a.1 -m \"Tag version 0.1.0-a.1\"
-$ git push --follow-tags
-
-# Version 0.1.0-a.1 is now public.
-
-$ edit manifest  # change 'version: 0.1.0-a.1.z'
-$ git commit -a -m \"Change version to 0.1.0-a.1.z\"
-$ git push
-
-# Master is now open for business.
-\
-
-\N|In the future release management will be automated with a
-\c{bdep-release(1)} command.|
-
-Notice also that when specifying a snapshot version in \c{manifest} we use the
-special \cb{z} snapshot value (for example, \c{0.1.0-a.1.z}) which is
-recognized and automatically replaced by \c{build2} with, in case of \c{git},
-a commit timestamp and id (refer to \l{b#module-version Version Module} for
-details).
-
-Publishing the final release is exactly the same. For completeness, here
-are the commands:
-
-\
-$ edit manifest  # change 'version: 0.1.0'
-$ git commit -a -m \"Release version 0.1.0\"
-$ git tag -a v0.1.0 -m \"Tag version 0.1.0\"
-$ git push --follow-tags
-
-$ edit manifest  # change 'version: 0.2.0-a.0.z'
-$ git commit -a -m \"Change version to 0.2.0-a.0.z\"
-$ git push
-\
-
-\N|One sticky point of continuous versioning is choosing the next version.
-For example, above should we continue with \c{0.1.1-a.0}, \c{0.2.0-a.0},
-or \c{1.0.0-a.0}? The important rule to keep in mind is that we can jump
-forward to any further version at any time and without breaking continuous
-versioning. But we can never jump backwards.
-
-For example, we can start with \c{0.2.0-a.0} but if we later realize that this
-will actually be a new major release, we can easily change it to
-\c{1.0.0-a.0}. As a result, the general recommendation is to start
-conservatively by either incrementing the patch or the minor version
-component. The recommended strategy is to increment the minor component and,
-if required, release patch versions from a separate branch (created by
-branching off from the release commit).
-
-Note also that you don't have to make any pre-releases if you don't need them.
-While during development you would still keep the version as \c{X.Y.Z-a.0}, at
-release you simply change it directly to the final \c{X.Y.Z}.|
-
-When publishing the final release you may also want to clean up now
-obsolete pre-release tags. For example:
-
-\
-$ git tag -l 'v0.1.0-*' | xargs git push --delete origin
-$ git tag -l 'v0.1.0-*' | xargs git tag --delete
-\
-
-\N|While at first removing such tags may seem like a bad idea, pre-releases
-are by nature temporary and their use only makes sense until the final release
-is published.
-
-Also note that having a \c{git} repository with a large number of published
-but unused version tags may result in a significant download overhead.|
-
-Let's also briefly discuss in which situations we should increment each of the
-version components. While \i{semver} gives basic guidelines, there are several
-ways to apply them in the context of C/C++ where there is a distinction
-between binary and source compatibility. We recommend that you reserve
-\i{patch} releases for specific bug fixes and security issues that you can
-guarantee with a high level of certainty to be binary-compatible. Otherwise,
-if the changes are source-compatible, increment \i{minor}. And if they are
-breaking (that is, the user code likely will need adjustments), increment
-\i{major}. During early development, when breaking changes are frequent, it is
-customary to use the \c{0.Y.Z} versions where \c{Y} effectively becomes the
-\i{major} component. Again, refer to the \l{b#module-version Version Module}
-for a more detailed discussion of this topic.
-
-\h#guide-consume-pkg|Package Consumption|
-
-Ok, now that we have published a few releases of \c{hello}, how would the
-users of our project get them? While they could clone the repository and use
-\c{bdep} just like we did, this is more of a development rather than
-consumption workflow. For consumption it is much easier to use the package
-dependency manager, \l{bpkg(1)}, directly.
-
-First, we create a suitable build configuration with the
-\l{bpkg-cfg-create(1)} command. We can use the same place for building all our
-tools so let's call the directory \c{tools}. Seeing that we are only
-interested in using (rather than developing) such tools, let's build them
-optimized and also configure a suitable installation location:
-
-\
-$ bpkg create -d tools cc        \
-  config.cxx=g++                 \
-  config.cc.coptions=-O3         \
-  config.install.root=/usr/local \
-  config.install.sudo=sudo
-created new configuration in /tmp/tools/
-
-$ cd tools
-\
-
-\N|The \c{bdep} build configurations we were creating with \c{init\ -C} are
-actually \c{bpkg} build configurations. In fact, underneath, \l{bdep-init(1)}
-calls \l{bpkg-cfg-create(1)}.|
-
-To fetch and build packages (as well as all their dependencies) we use the
-\l{bpkg-pkg-build(1)} command. We can use either an archive-based repository
-like \l{https://cppget.org cppget.org} or build directly from \c{git}:
-
-\
-$ bpkg build hello@https://git.build2.org/hello/hello.git
-fetching from https://git.build2.org/hello/hello.git
-  new libformat/1.0.0 (required by libhello)
-  new libprint/1.0.0 (required by libhello)
-  new libhello/1.1.0 (required by hello)
-  new hello/1.0.0
-continue? [Y/n] y
-configured libformat/1.0.0
-configured libprint/1.0.0
-configured libhello/1.1.0
-configured hello/1.0.0
-c++ libprint-1.0.0/libprint/cxx{print}
-c++ hello-1.0.0/hello/cxx{hello}
-c++ libhello-1.1.0/libhello/cxx{hello}
-c++ libformat-1.0.0/libformat/cxx{format}
-ld libprint-1.0.0/libprint/libs{print}
-ld libformat-1.0.0/libformat/libs{format}
-ld libhello-1.1.0/libhello/libs{hello}
-ld hello-1.0.0/hello/exe{hello}
-updated hello/1.0.0
-\
-
-\N|Passing a repository URL to the \c{build} command is a shortcut to the
-following sequence of commands:
-
-\
-$ bpkg add https://git.build2.org/hello/hello.git  # add repository
-$ bpkg fetch                             # fetch package list
-$ bpkg build hello                       # build package by name
-\
-
-|
-
-Once built, we can install the package to the location that we have specified
-with \c{config.install.root} using the \l{bpkg-pkg-install(1)} command:
-
-\
-$ bpkg install hello
-...
-install libformat-1.0.0/libformat/libs{format}
-install libprint-1.0.0/libprint/libs{print}
-install libhello-1.1.0/libhello/libs{hello}
-install hello-1.0.0/hello/exe{hello}
-
-$ hello World
-Hello, World!
-\
-
-\N|If on your system the installed executables don't run from \c{/usr/local}
-because of the unresolved shared libraries (or if you are installing somewhere
-else, such as \c{/opt}), then the easiest way to fix this is with \i{rpath}.
-Simply add the following configuration variable when creating the build
-configuration (or as an argument to the \c{install} command):
-
-\
-config.bin.rpath=/usr/local/lib
-\
-
-|
-
-If we need to uninstall a previously installed package, there is the
-\l{bpkg-pkg-uninstall(1)} command:
-
-\
-$ bpkg uninstall hello
-uninstall hello-1.0.0/hello/exe{hello}
-uninstall libhello-1.1.0/libhello/libs{hello}
-uninstall libprint-1.0.0/libprint/libs{print}
-uninstall libformat-1.0.0/libformat/libs{format}
-...
-\
-
-To upgrade or downgrade packages we again use the \c{build} command. Here
-is a typical upgrade workflow:
-
-\
-$ bpkg fetch              # refresh available package list
-$ bpkg status             # see if new versions are available
-
-$ bpkg uninstall hello    # uninstall old version
-$ bpkg build     hello    # upgrade to the latest version
-$ bpkg install   hello    # install new version
-\
-
-Similar to \c{bdep}, to downgrade we have to specify the desired version
-explicitly. There are also the \c{--upgrade|-u} and \c{--patch|-p} as well as
-\c{--immediate|-i} and \c{--recursive|-r} options that allow us to upgrade or
-patch packages that we have built and/or their immediate or all dependencies
-(see \l{bpkg-pkg-build(1)} for details). For example, to make sure everything
-is patched, run:
-
-\
-$ bpkg fetch
-$ bpkg build -pr
-\
-
-If a package is no longer needed, we can remove it from the configuration with
-\l{bpkg-pkg-drop(1)}:
-
-\
-$ bpkg drop hello
-following dependencies were automatically built but
-will no longer be used:
-  libhello
-  libformat
-  libprint
-drop unused packages? [Y/n] y
-  drop hello
-  drop libhello
-  drop libformat
-  drop libprint
-continue? [Y/n] y
-purged hello
-purged libhello
-purged libformat
-purged libprint
-\
-"
-- 
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