How do I embed Mercurial tags into my C/C++ code?

Question

Hi,

I would like to know if there is a way to embed Mercurial tags into my C/C++ code. Basically I would like the tag string, which will end up being a release number (major.minor.rev), to be automatically inserted in a determined location of my C code as a static string.

The overall objective is that the application could be queried about its version number when executed with say a '-v' command line argument. Any alternative approach that doesn't involve trying to embed a Mercurial tag will be also welcomed as an answer.

BTW, I am using Code::Blocks on a Linux environment, so the solution can not rely on fancy VStudio features.

Thanks!

Answer 1

We use a macro for this

#define CVS(a) static const volatile char *rcsid = a;

....
CVS("$Id$")

CVS automagically expands $Id$. I assume this is what mercurial tags work as well.

Then we can use the strings command to find the exact version of each file in the executable / library etc.

You could use something similar.

static const volatile char *rcsid = "$Id"; //or whatever mercurial tag you want

int main() {

    .....
    std::cout << "Version is " << rcsid << std::endl;
}

Answer 2

You will need the KeywordExtension to allow expansion of keyword entries, it is bundled with mercurial.

For instance to get support for $Id$ you could edit hgrc for you repo (.hg/hgrc) and add:

[extensions]
keyword =

[keyword]
# Enable expansion for the specific files
myfile.cpp =
# Enable for all .h files
**.h =

Then run

hg kwexpand

to expand keywords the relevant files, or

hg kwshrink

to shrink keywords.

You can even create your own keywords by adding the [keywordmaps] entry, e.g.

[keywordmaps]
User = {author|user}

Note: This disables the builtin keywords

More details on the extension can be found here: http://mercurial.selenic.com/wiki/KeywordExtension

Answer 3

While it's OS X oriented, there's a blog post describing how to add version info into your buids (without RCS style keywords).