Re: ediff maximum line length?

[Giorgos Keramidas <keramida@ceid.upatras.gr>]

On Thu, 10 Feb 2011 23:48:55 -0500, Stefan Monnier <monnier@iro.umontreal.ca> wrote:
>> ediff-mode highlights nicely all fine diffs within lines, using a
>> different face and this has proven *very* useful in many cases, but
>> I've now bumped on a case (and it will be often the case with some of
>> the stuff I'm lately doing) where ediff does not display fine diffs
>> for *very* long lines...
>
> I don't know ediff very much, but diff-mode also highlights fine diffs
> (via diff-refine-hunk or diff-auto-refine-mode, for example).  I know
> this code fairly well since I wrote it, and to the best of my
> knowledge it should not care about line-length (tho I haven't checked
> its efficiency in the presence of very long lines).

That's good to know. Thank you.

I am looking for something that can compare two files, so that I can
launch Emacs as my diff tool, e.g. from Perforce, Subversion, etc.  I
don't know if diff-mode can compare two files instead of a buffer and
its file.  That's why I used ediff.  (Another reason is that I know its
key bindings from vc, but that's not something I can't live without.)

Right now I have a small shell script as a wrapper that does something
like this simplified version:

    if test -d "$1"/. && test -d "$2"/. ; then
        exec emacs --eval "(ediff-directories \"$1\" \"$2\" nil)"
    else
        exec emacs --eval "(ediff-files \"$1\" \"$2\")"
    fi

Is it possible to use diff-mode for the same sort of comparison?