Re: git-rm isn't the inverse action of git-add

From: Junio C Hamano <gitster@pobox.com>
Date: Jul 11, 2007, 21:26 UTC
Message-ID: <7vps2y3a4n.fsf@assigned-by-dhcp.cox.net>
In-Reply-To: <20070711185644.GA3069@efreet.light.src>

Jan Hudec <bulb@ucw.cz> writes:

Show 5 quoted lines

> If index matches any of that, but the working tree version does not match any
> parent, the index entry should be removed (which currently isn't -- that's
> the proposed change), but the file left in wokring tree. That would make
> git-add + git-rm get you right back where you started, with nothing in index
> and unversioned file in working tree.

Don't think of 'rm' as inverse of 'add'. That would only confuse you.

A natural inverse of 'add' is 'un-add', and that operation is called 'rm --cached', because we use that to name the option to invoke an "index-only" variant of a command when the command can operate on index and working tree file (e.g. "diff --cached", "apply --cached").

A life of a file that does _not_ make into a commit goes like this:

	[1]$ edit a-new-file

This is 'create', not 'add'.  git is not involved in this step.

	[2]$ git add a-new-file

This is 'add'; place an existing file in the index. When you do not want it in the index, you 'un-add' it.

	[3]$ git rm --cached a-new-file

This removes the entry from the index, without touching the working tree file. If you do not want that file at all (as opposed to, "I am making a series of partial commits, and the addition of this path does not belong to the first commit of the series, so I am unstaging"), this is followed by

	[4]$ rm -f a-new-file

Again, git is not involved in this step.

The thing is, people sometimes want to have steps 3 and 4 combined, and it meshes well with the users' expectation when they see the word "rm". Think of "git rm" without "--cached" as a shorthand to do 3 and 4 in one go to meet that expectation.

Obviously, we cannot usefully combine steps 1 and 2. We could have "git add --create a-new-file" launch an editor to create a new file, but that would not be very useful in practice.

The fact that steps 3 and 4 can be naturally combined, but steps 1 and 2 cannot be, makes "add" and "rm" not inverse of each other.