GNU bug report logs - #58513
describe-function should say that defconst variables are constant

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Message #26 received at 58513 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: Phil Sainty <psainty <at> orcon.net.nz>, Stefan Kangas <stefan <at> marxist.se>,
 58513 <at> debbugs.gnu.org
Subject: Re: bug#58513: describe-function should say that defconst variables
 are constant
Date: Fri, 14 Oct 2022 16:25:30 +0200

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

> FWIW, my own local Emacs has `defconst` create actually
> constant variables by adding a `SYMBOL_DEFCONST` to `enum
> symbol_trapped_write`.  Admittedly I didn't make them really constant:
> I allow a subsequent `defconst` to change the value set by a previous
> `defconst`, but `setq` signals an error just like it does if you try to
> `setq` on `enable-multibyte-characters` or on `nil`.

Hm...  do you know if there's a performance impact from doing this?

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