save-match-data's return value

save-match-data's return value

[Juanma Barranquero]

save-match-data is implemented via unwind-protect and progn; however,
its docstring does not make any reference regarding the value returned
after its execution, though presumably it'll be the last form in BODY,
as in with-temp-buffer, et al.

Is that a part of the interface of save-match-data, and should be
documented, or does it specifically *no* guarantee about the value it
returns?


                                                           /L/e/k/t/u


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Re: save-match-data's return value

[Stefan Monnier]

> save-match-data is implemented via unwind-protect and progn; however,
> its docstring does not make any reference regarding the value returned
> after its execution, though presumably it'll be the last form in BODY,
> as in with-temp-buffer, et al.
> 
> Is that a part of the interface of save-match-data, and should be
> documented, or does it specifically *no* guarantee about the value it
> returns?

Lots of Emacs code relies on it and there is no other meaningful
value to return, so it's just an omission in the documentation.

AFAIK This behavior is shared by all `save-*' and `with-*' macros
and special forms.


	Stefan


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Re: save-match-data's return value

[Juanma Barranquero]

On Tue, 19 Feb 2002 11:27:28 -0500, "Stefan Monnier" <monnier+gnu/emacs@RUM.cs.yale.edu> wrote:

> Lots of Emacs code relies on it and there is no other meaningful
> value to return, so it's just an omission in the documentation.

I supposed as much.

> AFAIK This behavior is shared by all `save-*' and `with-*' macros
> and special forms.

Yes, I know, that's why I mentioned with-temp-buffer.


                                                           /L/e/k/t/u


2002-02-19  Juanma Barranquero  <lektu@terra.es>

	* subr.el (save-match-data): Doc fix.

Index: subr.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/subr.el,v
retrieving revision 1.287
diff -u -b -r1.287 subr.el
--- subr.el	6 Feb 2002 23:05:44 -0000	1.287
+++ subr.el	19 Feb 2002 17:04:59 -0000
@@ -1450,7 +1450,8 @@
 ;; We used to use an uninterned symbol; the compiler handles that properly
 ;; now, but it generates slower code.
 (defmacro save-match-data (&rest body)
-  "Execute the BODY forms, restoring the global value of the match data."
+  "Execute the BODY forms, restoring the global value of the match data.
+The value returned is the value of the last form in BODY."
   ;; It is better not to use backquote here,
   ;; because that makes a bootstrapping problem
   ;; if you need to recompile all the Lisp files using interpreted code.


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