From: Arthur Miller <arthur.miller@live.com>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: emacs-devel@gnu.org
Subject: Re: Q: BLV for function slots + BL obarray/hmap for symbol lookup?
Date: Sun, 30 May 2021 14:17:08 +0200 [thread overview]
Message-ID: <AM9PR09MB497776A46D6CDAD50AA259F596209@AM9PR09MB4977.eurprd09.prod.outlook.com> (raw)
In-Reply-To: <jwvo8ctymld.fsf-monnier+emacs@gnu.org> (Stefan Monnier's message of "Sat, 29 May 2021 22:44:59 -0400")
Stefan Monnier <monnier@iro.umontreal.ca> writes:
> Arthur Miller [2021-05-30 04:30:24] wrote:
>> Stefan Monnier <monnier@iro.umontreal.ca> writes:
>>>>>> (setq-local obarray (obarray-copy obarray))
>>> [...]
>>>> (setq-local obarray (copy-sequence obarray))
>>>
>>> obarray-copy != copy-sequence
>> My Emacs 27.1 says void function obarray-copy,
>
> Indeed, it's not provided.
>
>> but copy-sequence worked.
>
> Not really, no. You just haven't noticed the breakage yet.
Shallow copy, as Michael pointed it out? I'll see to update my Emacs.
>> Aren't obarray just vectors?
>
> No, they're very special vectors. E.g.:
>
> (let ((oa (make-vector 1 nil)))
> (intern "foo" oa)
> (intern "bar" oa)
> (intern "baz" oa)
> oa)
>
> ==>
>
> [baz]
>
> Yet, `foo` and `bar` are definitely still in there.
Yes, manual says use size 0 when making an obarray, so I understand the
space is allocated elsewhere, when interning is happening.
>> For your previous mail; yes I am quite aware this is very use-case
>> specific solution. Anything done elsewhere, outside that particular
>> buffer after the copy is performed will not be visible in that buffer,
>> as well as no definition will escape to rest of the Emacs, so this
>> buffer can only be used to change state of this particular buffer and
>> nothing else, and that can be quite brittle. For the bad and good. I
>> haven't experimented enough yet, just a bit, I am not sure how it will
>> work with Emacs state internally, gc? etc.
>
> AFAIK I think it can be made to work, yes.
> I don't expect any problem from "Emacs state internally" or the GC.
>
> The only source of trouble I can foresee is if "normal code" ends up
> running while your obarray is the one held in the global `obarray` var.
> This is because "normal code" will occasionally load files (via
> `require` or autoloads, typically) and that can quickly lead to
> confusion.
>
Allright, thanks for the clarifications.
next prev parent reply other threads:[~2021-05-30 12:17 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-22 21:46 Q: BLV for function slots + BL obarray/hmap for symbol lookup? Arthur Miller
2021-05-22 22:30 ` Stefan Monnier
2021-05-22 23:31 ` Arthur Miller
2021-05-23 3:25 ` Stefan Monnier
2021-05-23 9:00 ` Arthur Miller
2021-05-23 15:27 ` Stefan Monnier
2021-05-23 16:23 ` Arthur Miller
2021-05-29 7:31 ` Arthur Miller
2021-05-29 12:44 ` Michael Heerdegen
2021-05-30 2:57 ` Arthur Miller
2021-05-30 12:44 ` Philipp
2021-05-29 13:47 ` Stefan Monnier
2021-05-30 2:30 ` Arthur Miller
2021-05-30 2:44 ` Stefan Monnier
2021-05-30 12:17 ` Arthur Miller [this message]
2021-05-29 13:56 ` Stefan Monnier
2021-05-23 18:22 ` Clément Pit-Claudel
2021-05-23 20:23 ` Arthur Miller
2021-05-23 21:41 ` Clément Pit-Claudel
2021-05-24 12:37 ` Arthur Miller
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