Re: git should not use a default user.email config value

From: Jeff King <peff@peff.net>
Date: Aug 14, 2013, 07:40 UTC
Message-ID: <20130814074035.GB5095@sigill.intra.peff.net>
In-Reply-To: <vpqsiycn33b.fsf@anie.imag.fr>

On Wed, Aug 14, 2013 at 09:28:24AM +0200, Matthieu Moy wrote:

Show 17 quoted lines

> Junio C Hamano <gitster@pobox.com> writes:
> 
> > Jeff King <peff@peff.net> writes:
> >
> >> I guess we could do something like:
> >>
> >>   [include "repo:...your regex here..."]
> >>     path = .gitconfig-only-for-some-repos
> >>   [include "env:USE_MY_MAGIC_CONFIG"]
> >>     path = .gitconfig-only-when-magic-env-set
> >
> > I am not sure if "env" is very useful, but there certainly are other
> > possibilities (e.g. apply this only on this host, only for members
> > of this UNIX group, etc.)
> 
> I have already wished I had "git version >= XXX" here (but that's tricky
> to implement).

I assume it is "because version XXX understands config option Y, but older versions do not"[1]. Rather than ask for version XXX, then, you could ask for

  [include "option:Y"]
    path = ...

and versions which understand Y (which happens to be XXX or greater) would internally know that and consider the conditional true.

This whole discussion is basically implementing conditional config. In my patch, the conditional is limited only to including other config. But if you have many such conditions (and especially if each one only has one varying config key), the result can be unwieldy. Another way of doing this would be to introduce a conditional syntax to ignore or respect some part of the file. The problem is that it would be tricky to do in a backwards-compatible way.

-Peff

[1] I used to run into this with pager.*, which originally could only be
    a bool, but later learned to take custom pagers. I solved it with:

      git config --file .gitconfig-pager pager.diff ...
      git config --global include.path .gitconfig-pager

    which does not need a version or option conditional, because the
    option was added _before_ the include feature. IOW, older versions
    of git ignore it, and any which actually respect the include will
    know how to handle custom pagers. But that does not work with
    changes that came after the include feature was added. :)