Re: git-diff between /dev/null and blob

[Jakub Narebski <jnareb@gmail.com>]

Junio C Hamano wrote:

> Jakub Narebski <jnareb@gmail.com> writes:
> 
>> Currently, due to artifact of git-diff argument parsing you can get diff 
>> of two arbitrary blobs given by their sha1 id, e.g.
>>   git diff ab8050ceb4e43522e858768cc2c02fcb91839370 fd05278808d458602587bb024a48726018d30926
> 
> Just FYI, it is pretty much by design not artifact to allow
> something like this:
> 
>       git diff master:Makefile next:Makefile

Which we could get using

        git diff master next -- Makefile

Currently ('next' branch) git-diff manpage talks only about comparing trees.

* When  no  <ent>  is given, the working tree and the index file is compared,
  using git-diff-files.

* When one <ent> is given, the working tree and the named tree  is  compared,
  using git-diff-index. The option --cached can be given to compare the index
  file and the named tree.

* When  two  <ent>s  are  given,  these  two   trees   are   compared   using
  git-diff-tree.

And the only way to compare blobs is by giving directly or indirectly 
(like above) sha1 of the blobs, i.e. only the third case is supported. 

git-diff doesn't understand :<stage>:<filename> and :<filename> for
accessing index version of blob (git-cat-file for example understands
it). Note: <filename> in <revision>:<filename> and <stage>:<filename>
must be wrt GIT_DIR.

It is also no way to specify working tree version of file (blob). We 
could use ::<filename> for that, I think...

-- 
Jakub Narebski
Warsaw, Poland
ShadeHawk on #git