Re: builtin command's prefix question

From: Junio C Hamano <gitster@pobox.com>
Date: Dec 5, 2007, 23:22 UTC
Message-ID: <7vk5nsloa8.fsf@gitster.siamese.dyndns.org>
In-Reply-To: <7vlk88n648.fsf@gitster.siamese.dyndns.org>

Junio C Hamano <gitster@pobox.com> writes:

Show 7 quoted lines

>  * I would say it is a misconfiguration if GIT_DIR is not set and
>    GIT_WORK_TREE is, as the sole purpose of GIT_WORK_TREE is so that you
>    can work from a subdirectory when you set GIT_DIR.  I may be missing
>    an obvious use case that this is useful, but I do not think of any.
>    Dscho may be able to correct me on this, as he fixed up the original
>    work tree series that was even messier quite a bit during the last
>    round.

I had a short discussion with Dscho on this. One scenario that was brought up was this.

You have a work tree of mixed contents that logically belong to separate repository. Think $HOME/.?*, and tracking .vimrc and .pinerc as separate "projects". You have $HOME/gits/vim.git and $HOME/gits/pine.git bare-looking repositories.

The "kosher" way of doing this might be:

        $ cd $HOME
        $ GIT_WORK_TREE=$HOME; export GIT_WORK_TREE
        $ edit .vimrc
        $ GIT_DIR=gits/vim.git git commit .vimrc
        $ edit .pinerc
        $ GIT_DIR=gits/pine.git git commit .pinerc

However, if we define setup() to behave this way when GIT_DIR is not defined and GIT_WORK_TREE is:

 (1) internally pretend as if GIT_DIR was specified to be the
     directory where the command was started from (iow, do getcwd()
     once upon startup);

 (2) chdir to GIT_WORK_TREE (which means "callers of setup() always
     run from the top of the work tree");

 (3) set prefix to NULL;

Then this workflow becomes possible:

	$ cd $HOME
        $ GIT_WORK_TREE=$HOME; export GIT_WORK_TREE
	$ edit .vimrc .pinerc
        $ cd $HOME/gits/vimrc.git && git commit .vimrc
        $ cd $HOME/gits/pinerc.git && git commit .pinerc

I am not convinced this is giving any natural user experience, nor an alternative:

	$ cd $HOME
        $ GIT_WORK_TREE=$HOME; export GIT_WORK_TREE
        $ cd $HOME/gits/vimrc.git
	$ edit $HOME/.vimrc
        $ git commit .vimrc
        $ cd $HOME/gits/pinerc.git
	$ edit $HOME/.pinerc
        $ git commit .pinerc

While I still think the combination is simply crazy and does not make any sense, if enough users on the list agrees that it makes sense, I wouldn't mind setup() did (1) to (3) mentioned above. The alternative is simply to declare GIT_WORK_TREE without GIT_DIR is a nonsense and either error error out or ignore GIT_WORK_TREE, which might be easier to explain to people.

Opinions?