Re: [PATCH] mergetool: support absolute paths to tools by git config merge.<tool>path

[Steffen Prohaska <prohaska@zib.de>]

On Oct 8, 2007, at 11:57 PM, Theodore Tso wrote:

> On Mon, Oct 08, 2007 at 11:22:40PM +0200, Steffen Prohaska wrote:
>> This commit adds a mechanism to provide absolute paths to the
>> commands called by 'git mergetool'. A path can be specified
>> in the configuation variable merge.<toolname>path.
>
> This patch doesn't work if the config file doesn't specify an explicit
> mergetool via merge.tool.   The reason for that is this loop:
>
>     for i in $merge_tool_candidates; do
>         if test $i = emerge ; then
>             cmd=emacs
>         else
>             cmd=$i
>         fi
>         if type $cmd > /dev/null 2>&1; then
>             merge_tool=$i
>             break
>         fi
>     done
>
> is only checking to see if $cmd is in the path; it's not looking up
> the merge.<toolname>path variable in this loop.

I didn't change the automatic detection. It should work as before.
That is it continues to assume that merge tools are in PATH.

Is you expectation that git-mergetool should also consider the
absolute paths provided in merge.<toolname>path?

When I wrote the patch I had in mind that people will set the
merge.tool explicitly if they provide an absolute path. Automatic
detection would only be used if nothing is configured. In this
case a tool must be in PATH or would not be found.


> I guess the other question is whether we would be better off simply
> telling the user to specify an absolute pathname in merge.tool, and
> then having git-mergetool strip off the directory path via basename,
> and then on window systems, stripping off the .EXE or .COM suffix, and
> then downcasing the name so that something like "C:\Program
> Files\ECMerge\ECMerge.exe" gets translated to "ecmerge".  Would I be
> right in guessing that the reason why you used merge.<toolname>path
> approach was to avoid this messy headache?

Yes. The program to start ECMerge on Windows is called 'guimerge.exe'.
Hard to derive a sensible short name from this.

So I don't think that an automatic translation is an option. I prefer
to provide the absolute paths.

Absolute paths have another advantage. You can set several of them
and choose a tool on the command line. Maybe you have several tools
you want to try. Or you hacking with someone else who preferes a
different tool. Or you just want to give a demo. I see
merge.<toolname>path more as a database associating absolute paths
with the shortnames.

My mental model is as follows:
1) merge.tool selects the mechanism needed to call the tool, that is
command line arguments, how merge result is passed, ...
2) merge.<toolname>path provides additional information how to locate
the selected tool in the filesystem.

The two points are somewhat orthogonal. I'd not fuse them into one.

	Steffen