[PATCH 2 of 2 V2] extdiff: add --mode option

[Yuya Nishihara]

On Sat, 12 Jan 2019 09:26:25 -0800, Ludovic Chabant wrote:
> Thanks for the comments!
> 
> > Maybe need to check the .gui flag of the tool. Otherwise the console
> > would be messed up if the tool wasn't a GUI program.
> 
> Good point, although the existing extdiff code doesn't seem to be checking that, no? So should I do that in a separate patch?

A separate patch seems fine. To make clear, there's no need to check if the
tool is console-based or not unless multiple diff processes are spawned
simultaneously. Currently the .gui flag is tested only by filemerge.py.

> > Well, I think it will produce 8 modes,
> > dir-or-file x revpair-or-revrage x prompt-or-not.
> > 
> > And we can even get rid of the dir-or-file mode from command flags by
> > registering two tools, one for dir-diff and the other for per-file-diff.
> > I don't know if that is a better idea, but we'll never use the per-file
> > mode if the tool had a decent support for directory diff. So it's a tool-
> > specific property at some level.
> 
> It's not super important, but I disagree about the second-to-last-point here, since I actually wrote this patch with the intent of using per-file diffs with tools like BeyondCompare and vim+DirDiff, which both handle dir diffs pretty well. It's just that 95% of the time I want to see the diff of _all_ the files in a revision, and going through a dir-diff UI just adds unnecessary actions/clicks to get all those diffs to open.
> The only times I want a dir-diff where I'm going to only look at _some_ of the files is when diffing a big merge.
> 
> As a result, I was indeed planning on configuring per-file-diffing by default in my .hgrc for those tools, while occasionally passing a dir-diff argument when appropriate. Sure, I could make 2 different tools in my .hgrc if we didn't want to expose new options to the CLI, but for some reason it feels wrong to force users to edit their .hgrc for that.
> 
> I see your point about modes vs flags. Like I said, I don't have very strong opinions about it so I guess I'll change the second patch and use some flags instead. Are we going for --per-file and --confirm then?

To all, any thoughts?

I feel uncomfortable these days as there's little response to this kind of
UI patches. I'm not a good UI designer.

> Note that the tool config in .hgrc would look a bit less elegant as a result, like this:
> 
> cmd.blah=/path/to/blah
> opts.blah=--some-option -z
> per-file.blah=true
> confirm.blah=true
> 
> So instead I'm proposing a new config that specifies options for the hg extdiff command itself, like this:
> 
> cmd.blah=/path/to/blah
> opts.blah=--some-option -z
> hgopts.blah=--per-file --confirm
> 
> ...but I don't know if that opens up potential abuse or something.  What do you think?

The latter looks worse for me. Instead, you can use [alias] to pass in
arguments to hg commands.