# Re: Feature request: be able to pass arguments to difftool command

- From: Junio C Hamano \<hidden\>
- Date: 2018-08-28 19:37:45 
- List: git
- Page: https://ratatoskr.run/git/2018/08/7781760
- Thread: https://ratatoskr.run/git/2018/08/7781760/t.md

```text
"H.Merijn Brand" [ref] writes:

> So, my wish would be to have an option, possibly using -- to pass
> additional command line arguments to git difftool, so that
>
>  $ git difftool $commit~1..$commit -- -m -v2
>
> would pass the arguments after -- transparantly to ccdiff (in my case)

At the syntax level passing any option after "--" would be a no
starter, as I would imagine that "git difftool $revs -- $paths"
should still be supported.

At the concept level, however, I can see why such a feature would be
useful.  Perhaps

    $ git difftool --backend-option=-m --backend-option=-v2 HEAD
    $ git mergetool --backend-option=--foo

with appropriate way(s) [*1*] to make it easier to type (and
implement) would be an acceptable avenue to pursue, I wonder?


[Footnote]

*1* There are various possible ways, not all of them are mutually
    incompatible.

    a. Give a short-form synonym, e.g. -X, to "--backend-option";

    b. Assume that backend option always begins with a dash and add
       one when missing, e.g. -Xm becomes --backend-option=-m

    c. Allow giving multiple backend options on a single option and
       split at whitespace, e.g. --backend-option="-m -v2"

    d. Allow difftool.$toolname.opts configuration variable that is
       multi-valued, so you can say

	git -c difftool.ccdiff.opts=-v2 -c difftool.ccdiff.opts=-m difftool

       (of course, not necessarily from the command line but the
       point is you could configure it)

    Some of these (e.g. b, c) may not be desirable, though.

```