Re: Google Summer of Code 2013 (GSoC13)

Jeff King [off-list ref] writes:

This is not related to GSoC anymore, but I think handling multiple
versions is already pretty easy. You can just install to
"$HOME/local/git/$TAGNAME" or similar, and then symlink the "bin/git"
binary from there into your PATH as git.$TAGNAME (e.g., git.v1.7.8). Git
already takes care of the messy bits, like making sure sub-programs are
invoked from the same git version.

I already do this automagically with this script:

  https://github.com/peff/git/blob/meta/install/prefix

I just set "prefix" in the Makefile based on the script, and when I
"make install" tags or topic branches, they go to the right place (and
the "links" script in the same directory maintains the symlinks for me).

I never bothered to even submit those scripts to contrib, because I
figured they were so specific to my setup, and to keeping dozens of git
versions around (when debugging, it's nice to be able to check an old
version's behavior without even having to build it).

Yeah, I have been using the Make (in the todo branch, to be checked
out in Meta/ subdirectory of the working tree) script for exactly
this.  After tagging a release, I'd do

	git checkout -B snap v1.8.1.3
        Meta/Make install install-doc

to install them in $inst_prefix/git-snap-v1.8.1.3.  A "rungit"
script can then be used like:

	rungit v1.7.0 checkout blah

-- rungit script -- >8 -- rungit script --
#!/bin/sh
# Run various vintage of git

variant="${0##*/}" &&
: ${RUNGIT_BASE=$HOME/g/$(getarch)} &&
case "$variant" in
rungit)
	case $# in 
	0)
		echo >&2 "which version?"
		exit 1
		;;
	esac
	variant=$1
	shift
	;;
esac &&
case "$variant" in
-l)
	for d in "$RUNGIT_BASE/"git-*/bin/git
	do
		d=$(basename ${d%/bin/git})
		d=${d#git-}
		d=${d#snap-}
		echo "$d"
	done
	exit
	;;
git-*)
	variant=${variant#git-} ;;
v[0-9]*)
	variant=snap-$variant ;;
esac &&
d="$RUNGIT_BASE/git-$variant" &&
if test -f "$d/bin/git"
then
	exec "$d/bin/git" "$@"
else
	echo >&2 "$variant: No such variant for $a"
	exit 1
fi