diff options
| author | Boris Kolpackov <boris@codesynthesis.com> | 2022-03-23 06:58:52 +0200 |
|---|---|---|
| committer | Boris Kolpackov <boris@codesynthesis.com> | 2022-03-23 06:58:52 +0200 |
| commit | c1c80c10a8d469b2659015429c7695f3dbd51ef2 (patch) | |
| tree | a5aadf26a946bc399ca383dd1433675065ce6a6d | |
| parent | 566554303848b3015c87a05d8e1cff097d613a08 (diff) | |
Clarify config::save_*_omitted semantics
| -rw-r--r-- | libbuild2/config/utility.hxx | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/libbuild2/config/utility.hxx b/libbuild2/config/utility.hxx index bafcafa..cb82ea6 100644 --- a/libbuild2/config/utility.hxx +++ b/libbuild2/config/utility.hxx @@ -58,6 +58,10 @@ namespace build2 { // Mark a variable to be saved during configuration. // + // Note: the save_*_omitted flags work best when undefined or (one of) the + // omitted value(s) is the default (see a note in lookup_config() + // documentation for details). + // const uint64_t save_default_commented = 0x01; // Based on value::extra. const uint64_t save_null_omitted = 0x02; // Treat NULL as undefined. const uint64_t save_empty_omitted = 0x04; // Treat empty as undefined. @@ -242,9 +246,6 @@ namespace build2 // expensive. It is also ok to call both versions multiple times provided // the flags are the same. // - // @@ Should save_null_omitted be interpreted to treat null as undefined? - // Sounds logical. - // lookup lookup_config (scope& rs, const variable&, @@ -300,8 +301,14 @@ namespace build2 // or from the command line (i.e., it is inherited from the amalgamation), // then its value is "overridden" to the default value on this root scope. // - // @@ Should save_null_omitted be interpreted to treat null as undefined? - // Sounds logical. + // Note that while it may seem logical, these functions do not + // "reinterpret" defined values according to the save_*_omitted flags (for + // example, by returning the default value if the defined value is NULL + // and the save_null_omitted flag is specified). This is because such a + // reinterpretation may cause a diversion between the returned value and + // the re-queried config.* variable value if the defined value came from + // an override. To put another way, the save_*_omitted flags are purely to + // reduce the noise in config.build. // template <typename T> lookup |