David Aguilar <davvid@xxxxxxxxx> writes:
>> > Also, I don't think we should remove the ability for the user to
>> > choose which external diff tool to use.
>>
>> This is a larger concern. Does "difftool" allow use of an arbitrary tool
>> like how gitk does (I have a suspicion that it is not as flexible)?
>
> difftool supports arbitrary tools through configuration.
> For arbitrary tools we set difftool.$name.cmd and
> diff.tool = $name.
So it is not as flexible as just giving a command line template for
one-shot invocation, but that is Ok.
Don't get me wrong. I think the longer term direction should be to reduce
code from gitk without making lifes harder to existing users, and just
like built-in "diff --cc" stripped the combined-diff implemented in Tcl
from gitk, use of "difftool" would be a good way to unify the "diffing"
experience for a user who uses both command line and gitk at the same
time.
I do not read Tcl very well but I am guessing that in gitk you specify
what tool to run (e.g. "frobanodiff -z"), gitk feeds you two temporary
files on the filesystem to compare (e.g. "frobanodiff -z $tmp1 $tmp2"),
and your command line is responsible for giving satisfying diff experience
to the end user.
I see three possible approaches:
* Teach "git-difftool" a mode to compare two arbitrary files on the
filesytem, and set that as "External Diff" command that takes the
filenames as extra two parameters, just like any other "External Diff"
programs given to gitk does. This is the least palatable, as it won't
solve the read-only repository issue at all (it only allows you the
logic to choose the configured difftool backend program).
* Instead of disabling the traditional "External Diff" and taking it over
like your patch did, add a new codepath for "Difftool" that feeds the
commit IDs and paths the way git-difftool expects. The user can use
both, and the issue of read-only repository is solved when "Difftool"
is used (but not "External Diff").
* Take over "External Diff" codepath exactly like your patch did, but
teach "git-difftool" a new command line option to name an unconfigured
external program that takes two filenames. When "External Diff"
program is *not* configured in gitk, the command line to invoke
difftool would be exactly as in your patch, i.e. "difftool --no-prompt
$from $to -- $path". Otherwise, when gitk is configured to use an
external program, e.g. "frobanodiff -z", for "External Diff", you pass
that command line to "git-difftool" via that new option, e.g.
difftool --no-prompt --extcmd="frobanodiff -z" $from $to -- $path
Then difftool is responsible for preparing the two necessary temporary
files out of the given information ($from/$to/$path) and feeding them
to "frobanodiff -z" command line.
Maybe such --extcmd support already exists in difftool, in which case
my earlier suspicion that difftool is not as flexible would be false.
I think the last one would be the way to go in the longer term.
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