GNU bug report logs - #7408
23.2.1 dolist -- subr.el and cl-macs differ with nil-block return

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From: Štěpán Němec <stepnem <at> gmail.com>
To: Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: 7408 <at> debbugs.gnu.org, Jari Aalto <jari.aalto <at> cante.net>
Subject: bug#7408: Linux patchutils: Development of the project?
Date: Wed, 17 Nov 2010 13:47:04 +0100

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

>>> subr.el has had a dolist definition since at least Emacs 21.x; ie 9 years.
>>> Therefore this cannot be a major issue in practice.
>> In my book it is still a bug, no matter how many years ago this bug were
>> introduced:
>
>>     - To have two different implementations of same function.
>>     - To not be able to rely on uniform behavior.
>
> You look at it the wrong way: the problem is not with dolist, it's that
> you use `return' which is a special form that's not defined in standard
> Elisp.  After (require 'cl), `return' gets defined and things work as
> you expect.

While I don't share Jari's complaint in general (i.e., the approach "if
you only want the subr.el dolist, you don't care if it's really CL
dolist you end up calling; if you want the CL dolist, you require 'cl
and are done with it" has served me acceptably well), I've always
wondered what the hell was the person adding another function of the
same name thinking. To have a library that clobbers existing definitions
is a no no even outside Emacs, let alone in the core.

Is the explanation (I'm not familiar with the history) that at the time
cl.el was added there was no dolist in core Emacs, so there was no
perceived need to call it dolist* as in other similar cases (mapcar*,
defun* etc)? (In that case my sincere disdain would go for the person
who introduced dolist into subr.el later without addressing the naming
clash.)

Same with `dotimes'.

  Štěpán

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