Re: ediff customization: -w -B... + refinement

[Kevin Rodgers <ihs_4664@yahoo.com>]

Peter Tury wrote:
> I see different results in Emacs ediff and out-of-emacs command line
> diff.
> 
> I try to get rid of white space and new line diffs, so I tried diff -a
> -w -B --binary ... It produces the desired output in command line, but
> whitespace- and newline-differences are showed (and treated) in
> Emacs. Why? I set ediff-diff-options to "-a -w -B --binary", but it
> seems to be ignored? Why? How to get rid of such whitespace diffs? I
> tried ##, but nothing changed.
> 
> How can check what command was exactly sent by Emacs (to
> Windows/diff)? (If I check *ediff-diff*'s content, it is "wrong",
> i.e. shows result without -w -B...) And what diff is used? (I have an old
> diff also in my path, but I put the directory of the new diff before
> that old one's directory in the path variable.)

To see what diff program is used:

M-: (executable-find ediff-diff-program)

I don't think you can find out after the fact what command was run,
but you could see which options are used dynamically by examining the
4th argument passed to ediff-exec-process:

M-x debug-on-entry RET ediff-exec-process

Looking at its source code in ediff-diff.el, I find:

     ;; the --binary option, if present, should be used only for buffer jobs
     ;; or for refining the differences
     (or (string-match "buffer" (symbol-name ediff-job-name))
	(eq buffer ediff-fine-diff-buffer)
	(setq args (delete "--binary" args)))

So maybe you need to use M-x ediff-buffers instead of M-x ediff-files
to use the --binary option.

> My other question: what to do if I want refinement to show differences
> by chars and not by words?

Try: (setq ediff-forward-word-function 'forward-char)

> These makes ediff unusable for me now, because emacs shows totally
> wrong lines compared. E.g. if an empty line is deleted and following
> lines are reindented then I see (in ediff's windows) as if the
> (original) empty line would have been replaced with several new lines
> (what are in fact only reindented) and then the original lines are
> compared with other lines... :-( I think this is diff's feature, but
> can be handled in command line with switches -w -B -- but not in
> Emacs?

-- 
Kevin