patchgit-mergetool: Make default smarter by considering user's desktop environment and editor

Make git-mergetool prefer meld under GNOME, and kdiff3 under KDE. When considering emerge and vimdiff, check $VISUAL and $EDITOR to see which the user might prefer.

Signed-off-by: Josh Triplett <josh@freedesktop.org>
---

Arguably, kdiff3 should now move down next to meld, below the other non-graphical tools, so that if the user doesn't run KDE or GNOME they get a non-KDE, non-GNOME tool. This patch doesn't do that, though.

 git-mergetool.sh |   14 +++++++++++++-
 1 files changed, 13 insertions(+), 1 deletions(-)

Josh Triplett <josh@freedesktop.org> writes:

The basic idea is sound.  However...

 (1) I wonder if we can get rid of the horribly long if .. elif
     chain by using shell function and then iterate a list of them;

 (2) echo "${VISUAL-$EDITOR}" | grep '^emacs'???

     Some people may have explicit path (/home/me/bin/emacs),
     and/or runs a variant of emacs called 'xemacs'.  Same for
     vim.

Something like...

        test_xstuff () {
                test -n "$DISPLAY" && type "$1" >/dev/null 2>&1
        test_kdiff3 () {
                test_xstuff kdiff3
        }
        test_tkdiff () {
                test_xstuff tkdiff
        }
        test_estuff() {
                type "$1" >/dev/null 2>&1 &&
                case "${VISUAL-$EDITOR}" in *"$1"*) : ;; *) false ;; esac
        }
        test_emerge () {
                test_estuff emacs
        }
        test_vimdiff () {
                test_estuff vim
        }

        choose_merge_tool () {
                for t in "$@"
                do
                        if test_$t
                        then
                                echo "$t"
                                break
                        fi
                done
        }

        if test -z "$merge_tool"
        then
                merge_tool_candidates='kdiff3 tkdiff xxdiff meld opendiff ...'
                if test -n "$GNOME_DESCTOP_SESSION_ID"
                then
                        merge_tool_candidates="meld $merge_tool_candidates"
                elif test -n "$KDE_FULL_SESSION"
                then
                        merge_tool_candidates="kdiff3 $merge_tool_candidates"
                elif
                        ...
                fi
                merge_tool=$(choose_merge_tool $merge_tool_candidates)
        fi

Junio C Hamano <junkio@cox.net> writes:

Actually, a lot of people run as editor a program called "emacsclient" or "gnuclient": this one connects to an existing Emacs session and passes its arguments to it. And of course, this is what git-mergetool should then also do.

David Kastrup <dak@gnu.org> writes:

I do that too, but that is covered by the prefix rule Josh has, so it is Ok.

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

Another note: in my usual Emacs session, EDITOR is set to /usr/local/emacs-22/bin/emacsclient which would not be covered... So that should probably be

useemacs=0
for i in ${VISUAL-$EDITOR}
do
        case "`basename $i`" in [xX][eE]macs*|[eE]macs*|gnuclient*)
             useemacs=1
        esac
        break
done

This should work even when we are talking about something like EDITOR="C:\My Programs\XEmacs\gnuclient.exe" -n "C:\My Programs\XEmacs\XEmacs"

And it does not require starting grep for something which the shell can perfectly well handle on its own. Yes, it does need basename. I don't see a good way to avoid that.

This is what I've been experimenting in my tree; what do people think?

if test -z "$merge_tool" ; then
    if test -n "$DISPLAY"; then
	merge_tool_candidates="kdiff3 tkdiff xxdiff meld gvimdiff"
	if test "$GNOME_DESKTOP_SESSION_ID"x != ""x; then
	    merge_tool_candidates="meld $merge_tool_candidates"
	fi
	if test "$KDE_FULL_SESSION"x = "true"x; then
	    merge_tool_candidates="kdiff3 $merge_tool_candidates"
	fi
    fi
    if echo "${VISUAL:-$EDITOR}" | grep 'emacs' > /dev/null 2>&1; then
	merge_tool_candidates="$merge_tool_candidates emerge"
    fi
    if echo "${VISUAL:-$EDITOR}" | grep 'vim' > /dev/null 2>&1; then
	merge_tool_candidates="$merge_tool_candidates vimdiff"
    fi
    merge_tool_candidates="$merge_tool_candidates opendiff emerge vimdiff"
    echo "merge tool candidates: $merge_tool_candidates"
    for i in $merge_tool_candidates; do
	if test $i = emerge ; then
	    cmd=emacs
	else
	    cmd=$i
	fi
	if type $cmd > /dev/null 2>&1; then
	    echo merge_tool chosen is $i
	    merge_tool=$i
	    break
	fi
    done
fi

						- Ted