bug#11067: 24.0.94.1; diff-buffer-with-file

[Arni Magnusson]

Hi Stefan, thanks for the response.

Being able to set `diff-command' to any external program is a great 
feature in Emacs, in my experience. I have been using it for many Emacs 
versions, and I would miss this capability if it would be removed from 
Emacs 24.

In Windows I set `diff-command' to "winmerge" and in Linux I set it to 
"kompare". Next week I might set it to whatever I find the most efficient 
diff program for me.

This lets me view the differences in a feature-rich external diff program. 
I can visualize the differences between my modified buffer and saved state 
much more efficiently than with diff. Sure, diff is okay for visualizing 
the changes, ediff would be better, but really the external diff programs 
are much more efficient for me. My `ediff-mode-hook' is extensive, but I 
still find the external programs more efficient.

I understand that pure diff is, well, pure. But I remember how impressed 
and thankful I was when I disovered the flexibility of `diff-command', and 
I'm guessing many other Emacs users have found it practical to set it to 
something other than "diff". Comparing changes is an important task when 
editing, and it's great that Emacs can delegate this task to specialized 
programs, although the default is to handle things within Emacs.

Best regards,

Arni



On Fri, 23 Mar 2012, Stefan Monnier wrote:

> > http://alpha.gnu.org/gnu/emacs/windows/emacs-20120319-r107630-bin-i386.zip
> > and `diff-buffer-with-file' is not working like it did in Emacs 23.4.1
> > 1. Start emacs -Q
> > 2. Set `diff-command' to "winmerge" and `diff-switches' to nil
>
> It seems that's your problem: winmerge is not a replacement for `diff'
> because it does not accept the "-L <label>" argument of diff.
>
> Any particular reason to use winmerge rather than diff?  Does it let you
> view the diff in winmerge, or does it return a diff-style output in *diff*?
>
>
>        Stefan