Re: How to embed a hash, tag or branch name?

On Sat, 1 August 2009, Dirk Süsserott wrote:

Am 31.07.2009 11:52 schrieb Mikko Rapeli:

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On Fri, Jul 31, 2009 at 02:27:50AM -0700, Jakub Narebski wrote:

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You can embed SHA-1 of a _file contents_ (blob) using '$Id: $' keyword
with `ident` attribute - see gitattributes manpage.

Great, thanks!

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The correct solution of embedding version number is to do it at 
_build time_, using e.g. script similar to GIT-VERSION-GEN used by
Git itself and by Linux kernel.  It helps if you tag your releases.

Hi Mikko,

I don't know whether you want to use the "ident" command on your final
binary. With Git, that's pointless, as all source files will have the
same $Id$. So it's perfectly sufficient to have only ONE file enriched
with Git's SHA1.

You are wrong.  In Git $Id$ / $Id: $ expands to SHA-1 id of _blob_ 
(i.e. of file *contents*), not SHA-1 id of a commit.  This way when
switching branches or rewinding branch using git-reset we don't have
to pay huge performance penalty because of `ident`, as we would have
because every file would have to be changed if $Id$ was about commit
id (or if there was $Revision$ or $Author$ implemented).

Suggestion: During build time, compile (and link in) a file (e.g.
version.c) with "-DVERSION=\"$(git describe)\"". My version.c looks like
this:

GIT-VERSION-GEN and various tricks in Makefile do just that, not only
for compiled parts, but also for scripts.

[...]
-- 
Jakub Narebski
Poland