Re: [RFC] get_sha1() shorthands for blob/tree objects

[Junio C Hamano <junkio@cox.net>]

Linus Torvalds <torvalds@osdl.org> writes:

> Now, the thing that an internal "git diff" could do better is to notice 
> when it gets _one_ blob revision, and one filename, ie we could do
>
> 	git diff v0.99.6:git-commit-script git-commit.sh
>
> which parses as one SHA1 of a blob (put onto the rev.pending_objects 
> list), and one filename (in the rev.prune_data array). We could decide to 
> automatically do the "right thing" for that case too.

The "right thing" is ambiguous, I am afraid.

I think it would be natural to interpret the request as a diff
between the blob from v0.99.6 and a random working tree file, 
which may not even exist in the index.

However I suspect what you are getting at is to act as if the
user said:

	git diff v0.99.6:git-commit-script HEAD:git-commit.sh

Oh, another possibility is to act as if the user said

	git diff v0.99.6:this :git-commit.sh

where "(empty):" would stand for "look up in the index, not in a
tree".

I think these are all valid interpretations and there are useful
use cases (admittably the last one is "diff-cache --cached").

Unfortunatly, I do not think this parses well:

	git diff git-commit.sh v0.99.6:git-commit-script

but you could always say:

	git diff -R v0.99.6:git-commit-script git-commit.sh