Re: [WIP PATCH 0/5] support --exclude for diff/log commands

[Michael J Gruber <git@drmicha.warpmail.net>]

Nguyen Thai Ngoc Duy venit, vidit, dixit 21.03.2011 05:02:
> On Thu, Mar 10, 2011 at 5:05 PM, Nguyen Thai Ngoc Duy <pclouds@gmail.com> wrote:
>> 2011/3/10 Junio C Hamano <gitster@pobox.com>:
>>> Let's step back a bit.
>>>
>>> We chose to use ":/<regexp>" as one new form of extended SHA-1 expression
>>> to name an object for two reasons: (1) no normal <ref> can have a colon in
>>> it, because of check-ref-format restriction; (2) ":" is an unlikely letter
>>> to appear at the beginning of a pathname, and people with such a path can
>>> work around by saying "./:frotz" or "\:xyzzy".
>>>
>>> There is a disambiguation logic to check a list of arguments that lacks an
>>> explicit "--" separator to make sure that each element early on the list
>>> can only be interpreted as an object name but not as a pathname that
>>> exists on the filesystem, and all the remaining elements are pathnames
>>> that exist on the filesystem.
>>>
>>> If we introduce an extended syntax for pathspec and make the prefix magic
>>> character ":", and if we choose to use ":/" as one kind of magic, I was a
>>> bit worried that this may affect the disambiguation.  The users must use
>>> an explicit "--" when feeding a pathspec with the magic so that the parser
>>> knows which kind of magic (either object name magic or pathspec magic)
>>> they are talking about.
>>
>> Or.. we can consider this ':' a special form of wildcard and interpret
>> the same way:
>>
>>  - first try exact match. If it matches, the leading ':' is
>> interpreted literally as part of file name.
>>  - magic.
> 
> One thing that makes it different from Michael's approach is, :/foo
> will match ':/foo' literally in every directories and foo at top-tree.
> I feel mildly uncomfortable with it, but it makes it consistent with
> other wildcards. If no one objects, I'll try to make a patch with this
> approach.

Maybe I misunderstand which topic you are referring to. I have a patch
for ":" (to denote repo-root in pathspecs), there's no need to make
another one for ":/". (I would really prefer to do it myself since I
brought it up.) I was just waiting for agreement to settle in about
which prefix to use. Also, I have checked with J&J of mingw/msysgit fame
meanwhile to make sure that the notation does not create problems on the
windows side of git.

Michael