From: Helmut Eller <eller.helmut@gmail.com>
To: 8711@debbugs.gnu.org
Subject: bug#8711: 24.0.50; binding _ to unused values with lexical-binding
Date: Mon, 23 May 2011 22:32:56 +0200 [thread overview]
Message-ID: <m28vtxb1jb.fsf@gmail.com> (raw)
In-Reply-To: <m2lixzj3lp.fsf@gmail.com>
* Stefan Monnier [2011-05-23 19:29] writes:
> I think the same problem happens with dotimes/dolist using the old
> definition: the loop vars `key' and `value' are let-bound outside the
> loop and then setq'd at each loop iteration (it's this setq that causes
> them to be "not left unused"). This was OK for the dynamic scoping case
> because let-binding is significantly more costly than setq, but it is
> not right for the lexical scoping case where the cost of let is not
> higher than `setq' and where the semantic is actually then wrong:
> e.g. if you "collect (lambda () value)" the current code ends up
> returning a list of functions that all return the last `value', rather
> than a list of functions that each return one of the `values' in
> the alist.
BTW, is there a good reason why we can't disallow setq on closed over
variables in Elisp? That kind of mutability seems like a bad idea in a
concurrent world. Closures are a new feature so we could make a
conscious decision not to introduce the problematic mutable variables.
Helmut
next prev parent reply other threads:[~2011-05-23 20:32 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-21 18:44 bug#8711: 24.0.50; binding _ to unused values with lexical-binding Helmut Eller
2011-05-23 9:01 ` Lawrence Mitchell
2011-05-23 14:24 ` Stefan Monnier
2011-05-23 18:23 ` Helmut Eller
2011-05-23 19:29 ` Stefan Monnier
2011-05-23 20:16 ` Helmut Eller
2011-05-24 0:56 ` Stefan Monnier
2011-05-24 6:01 ` Helmut Eller
2011-05-24 12:42 ` Stefan Monnier
2011-06-02 11:17 ` Juanma Barranquero
2011-06-02 12:45 ` Stefan Monnier
2011-06-02 13:41 ` Juanma Barranquero
2011-06-02 14:00 ` Stefan Monnier
2011-06-02 17:10 ` Juanma Barranquero
2011-05-23 20:32 ` Helmut Eller [this message]
2011-05-24 0:51 ` Stefan Monnier
2022-05-08 12:33 ` bug#8711: bug#26960: 26.0.50; Complaints about unused variable in cl-destructuring-bind Lars Ingebrigtsen
2022-05-08 13:32 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-05-09 9:25 ` bug#8711: " Lars Ingebrigtsen
2022-05-09 12:26 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
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