Re: replace matches in any string

[Lars Magne Ingebrigtsen <larsi@gnus.org>]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

>> For one thing I guess it is too late to change the API.  For another,
>> that prevents strings from being garbage-collected as long as they are
>> present in some match-data.  While the same is true of buffers, a dead
>> buffer does not take significant space.
>
> We already save the matched object if it's a buffer, and no, the
> potential "space leak" is not a significant problem.

It's one string per match data, so it's not significant.

>> What's wrong with match-substitute-replacement ?
>
> Indeed, I had forgotten about it.

Oh, that exists?  Never mind, then.  :-)  So you already save all the
matched substrings in case somebody calls a the function
`match-substitute-replacement', which nobody has heard of (there's one
(1) use of the function in question in the Emacs sources...

Hang on.  This is the definition:

(defun match-substitute-replacement (replacement
				     &optional fixedcase literal string subexp)
  "Return REPLACEMENT as it will be inserted by `replace-match'.
In other words, all back-references in the form `\\&' and `\\N'
are substituted with actual strings matched by the last search.
Optional FIXEDCASE, LITERAL, STRING and SUBEXP have the same
meaning as for `replace-match'."
  (let ((match (match-string 0 string)))
    (save-match-data
      (set-match-data (mapcar (lambda (x)
				(if (numberp x)
				    (- x (match-beginning 0))
				  x))
			      (match-data t)))
      (replace-match replacement fixedcase literal match subexp))))

This doesn't help at all.

The use case is that you had some string do a match, but you don't have
access to the string variable.  You just want the matches that you know
were made, aka perlish $1, $2, $3.  I reiterate my first posting on this
issue as a feature request.

-- 
(domestic pets only, the antidote for overdose, milk.)
  larsi@gnus.org * Lars Magne Ingebrigtsen