Re: [Boost-build] Understanding generated files / targets.

Subject: Re: [Boost-build] Understanding generated files / targets.
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2014-07-27 18:27:42

AMDG

On 07/27/2014 12:42 PM, Tom wrote:
> I am trying to generate a C++ source (or header) file containing
> versioning information generated from 'git describe'.  This has become
> necessary as we have moved to git and a branched development model and
> modifying a version file manually is a non-starter (due to conflicts
> on merg) in this development model.  We will be driving the version
> number in binaries by tags in revision control.
> 
> This is challenging mainly in that the generated file depends on state
> not known (or knowable) by Boost.Build as opposed to a normal file
> transformation.  This results in either not generating the file when
> it should be (a tag is checked out or a file is edited which do not
> affect the code handling the version number, then the build is run) or
> in rebuilding things when it is not actually necessary (which causes
> all tests to be re-run for example).
> 
> I do also understand the 'notfile' rule and I don't think it applies.
> I am actually generating a real file, it just doesn't depend on any
> other sources.
> 

If you can use the print module to generate the file,
then it automatically checks whether the content has
changed.  (See b2 --help print for information on
how to use it)

In Christ,
Steven Watanabe