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authorKaren Arutyunov <karen@codesynthesis.com>2016-09-10 14:13:19 +0300
committerKaren Arutyunov <karen@codesynthesis.com>2016-09-10 14:13:19 +0300
commit985f1dde6afa6a42149118e6085325eacb1bd53e (patch)
tree9f0234366c61cc5c7fb60c6194350eb54909ba0d /butl
parent3aba9af9e68f22ab6291fc16986a215f3f75508d (diff)
Add sample usage with process to fdstream as a comment
Diffstat (limited to 'butl')
-rw-r--r--butl/fdstream58
1 files changed, 58 insertions, 0 deletions
diff --git a/butl/fdstream b/butl/fdstream
index 990cea0..bb5364b 100644
--- a/butl/fdstream
+++ b/butl/fdstream
@@ -182,6 +182,64 @@ namespace butl
// Note that ifdstream destructor will close an open file descriptor but
// will ignore any errors. To detect such errors, call close() explicitly.
//
+ // This is a sample usage of iofdstreams with process. Note that here it is
+ // expected that the child process reads from STDIN first and writes to
+ // STDOUT afterwards.
+ //
+ // try
+ // {
+ // process pr (args, -1, -1);
+ //
+ // try
+ // {
+ // // In case of exception, skip and close input after output.
+ // //
+ // ifdstream is (pr.in_ofd, fdstream_mode::skip);
+ // ofdstream os (pr.out_fd);
+ //
+ // // Write.
+ //
+ // os.close (); // Don't block the other end.
+ //
+ // // Read.
+ //
+ // is.close (); // Skip till end and close.
+ //
+ // if (pr.wait ())
+ // {
+ // return ...; // Good.
+ // }
+ //
+ // // Non-zero exit, diagnostics presumably issued, fall through.
+ // }
+ // catch (const failure&)
+ // {
+ // // IO failure, child exit status doesn't matter. Just wait for the
+ // // process completion and fall through.
+ // //
+ // // Note that this is optional if the process_error handler simply
+ // // falls through since process destructor will wait (but will ignore
+ // // any errors).
+ // //
+ // pr.wait ();
+ // }
+ //
+ // error << .... ;
+ //
+ // // Fall through.
+ // }
+ // catch (const process_error& e)
+ // {
+ // error << ... << e.what ();
+ //
+ // if (e.child ())
+ // exit (1);
+ //
+ // // Fall through.
+ // }
+ //
+ // throw failed ();
+ //
class LIBBUTL_EXPORT ifdstream: fdstream_base, public std::istream
{
public: