Re: RFC: a plugin architecture for git extensions?

[Jonathan Nieder <jrnieder@gmail.com>]

Junio C Hamano wrote:

> I was thinking it, and the location git-work binary gets installed, should
> depend on where "git" and its subcommand binaries are installed.  The word
> plug-in mentioned in the thread implied that whatever plugs in is not by
> itself full fledged thing that is useful standalone, so it seemed a very
> natural thing to do.

With the goal of making some commands available to git without putting
them on the $PATH in mind, this all makes more sense.  Sorry I missed
that before.

>> Or is the idea to blindly install (a symlink to) git-work to $(git
>> --exec-path)/ rather than a place on the $PATH?
>
> You can call it _blindly_ if you like, but that is what I meant.  "git"
> tells where the binary and help material for a "plugin" to be installed,
> so that it can find them where it expects to.

Right, my worry was based on the usual way programs find their way
onto my $PATH.  That is:

 - if they are installed via a package from the distro, they are in
   /usr/bin.

 - if they are installed with "make install" by the local sysadmin for
   all users, they are in /usr/local/bin.

 - if I am trying them out for myself, they are in $HOME/opt/foo/bin
   and when it is time to remove it, "rm -fr $HOME/opt/foo".

 - if I have adopted them, symlinks go in $HOME/bin.

With a local gcc-4.6 in $HOME/bin, if the sysadmin upgrades gcc so
gcc-4.6 is to appear in /usr/bin or /usr/local/bin, my setup still
works without trouble.  So, barring bugs, each installation method
does not interfere with the other ones.

Call it overengineering, but I would want a way for installing new git
commands to have the same attributes (installable by normal users in
multiuser systems and name conflicts not being a terrible
administrative burden).  A simple way would be to introduce
GIT_MAN_PATH as you described and to teach "git help" to accept a
GIT_EXEC_PATH consisting of a colon-delimited (semicolon-delimited on
Windows) list of directories.