From: Pip Cet <pipcet@gmail.com>
To: Paul Eggert <eggert@cs.ucla.edu>
Cc: "Basil L. Contovounesios" <contovob@tcd.ie>,
Stefan Monnier <monnier@iro.umontreal.ca>,
emacs-devel@gnu.org
Subject: Re: master f51f963: Fix some side-effecting uses of make-text-button
Date: Sun, 07 Jun 2020 09:21:17 +0000 [thread overview]
Message-ID: <87d06bxmcy.fsf@gmail.com> (raw)
In-Reply-To: <785d730e-23b2-dcad-105c-80ac5074b5dc@cs.ucla.edu> (Paul Eggert's message of "Sat, 6 Jun 2020 13:15:35 -0700")
Paul Eggert <eggert@cs.ucla.edu> writes:
> On 6/6/20 12:41 PM, Pip Cet wrote:
>
>> What I'm fighting against is a certain model of
>> immutability being installed into the Emacs source tree and effectively
>> preventing better ones from ever having a chance, as well as turning out
>> to be, as the vast majority of such models have, a problem rather than a
>> useful feature.
>
> I'm quite conscious of those dangers. What I had in mind was something
> far more
> limited: just supporting runtime checking of attempts to modify strings that
> either have undefined behavior if you mutate them now, or are close enough to
> that category so that nobody will care about the difference (except to
> be happy
> when Emacs catches unlikely glitches in their programs).
Okay, I'm looking forward to that proposal, and sorry for criticizing it
before I'd understood it clearly.
>> if we want that C API to be flexible enough to allow unusual
>> applications (and isn't that what Emacs is all about?), it needs
>> something more than just the obvious CHECK_MUTABLE (obj) macro.
>
> It sounds like you're thinking ahead to the non-string case.
I am.
> I'm
> limiting myself
> just to strings for now, as they're the most salient part of the problem (core
> dumps and all).
The core dumps definitely need to be fixed.
I still don't understand precisely how far you're planning to go in
protecting an immutable string's text properties, but you've convinced
me that it's a win in practice even if we just protect the characters.
> It should be OK to do that, and put off the
> more-general issues
> until later (if we ever do that at all).
So this would be only strings, not cons cells? That makes sense to me.
> The obvious check_string_mutable function doesn't need to be used very often:
> only in the places where CHECK_IMPURE is used on strings now. The only other
> primitive I've found the need for at the C level is freeze_string (to mark an
> already-constructed string as being a constant).
Just to be clear: there's no way to unfreeze a string, right? Because
that would add considerable complexity and not be worth it, IMHO.
next prev parent reply other threads:[~2020-06-07 9:21 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200604223056.17078.81265@vcs0.savannah.gnu.org>
[not found] ` <20200604223058.1850020A26@vcs0.savannah.gnu.org>
2020-06-04 22:44 ` master f51f963: Fix some side-effecting uses of make-text-button Stefan Monnier
2020-06-05 0:58 ` Paul Eggert
2020-06-05 9:27 ` Pip Cet
2020-06-05 10:51 ` Basil L. Contovounesios
2020-06-05 12:46 ` Pip Cet
2020-06-05 13:51 ` Basil L. Contovounesios
2020-06-05 14:31 ` Pip Cet
2020-06-05 15:48 ` Basil L. Contovounesios
2020-06-05 18:17 ` Paul Eggert
2020-06-06 8:18 ` Pip Cet
2020-06-06 16:57 ` Drew Adams
2020-06-06 17:57 ` Stefan Monnier
2020-06-06 19:00 ` Pip Cet
2020-06-06 19:49 ` Paul Eggert
2020-06-06 20:23 ` Drew Adams
2020-06-07 9:14 ` Pip Cet
2020-06-06 22:14 ` Stefan Monnier
2020-06-07 1:40 ` Paul Eggert
2020-06-07 15:24 ` Stefan Monnier
2020-06-07 23:42 ` Paul Eggert
2020-06-07 9:31 ` Pip Cet
2020-06-06 20:19 ` Drew Adams
2020-06-06 17:54 ` Paul Eggert
2020-06-06 19:41 ` Pip Cet
2020-06-06 20:15 ` Paul Eggert
2020-06-07 9:21 ` Pip Cet [this message]
2020-06-07 23:37 ` Paul Eggert
2020-06-06 20:11 ` Drew Adams
2020-06-06 22:16 ` Stefan Monnier
2020-06-06 23:27 ` Drew Adams
2020-06-05 13:02 ` Stefan Monnier
2020-06-05 13:50 ` Basil L. Contovounesios
2020-06-06 19:09 ` Paul Eggert
2020-06-06 20:19 ` Drew Adams
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