From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Eli Zaretskii <eliz@gnu.org>
Cc: emacs-devel@gnu.org
Subject: Re: creating unibyte strings
Date: Fri, 22 Mar 2019 08:33:02 -0400 [thread overview]
Message-ID: <jwvh8bvhzhs.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <83wokrs6en.fsf@gnu.org> (Eli Zaretskii's message of "Fri, 22 Mar 2019 10:41:04 +0300")
>> Which reminds me: could someone add to the module API a primitive to
>> build a *unibyte* string?
> I don't like adding such a primitive. We don't want to proliferate
> unibyte strings in Emacs through that back door, because manipulating
> unibyte strings involves subtle issues many Lisp programmers are not
> aware of.
I don't see what's subtle about "unibyte" strings, as long as you
understand that these are strings of *bytes* instead of strings
of *characters* (i.e. they're `int8[]` rather than `w_char_t[]`).
"Multibyte" strings are just as subtle (maybe more so even), yet we
rightly don't hesitate to offer a primitive way to construct them.
> Instead, how about doing that via vectors of byte values?
What's the advantage? That seems even more convoluted: create a Lisp
vector of the right size (i.e. 8x the size of your string on a 64bit
system), loop over your string turning each byte into a Lisp integer
(with the reverted API, this involves allocation of an `emacs_value`
box), then pass that to `concat`?
It's probably going to be even less efficient than going through utf-8
and back.
Think about cases where the module receives byte strings from the disk
or the network and need to pass that to `decode-coding-string`.
And consider that we might be talking about megabytes of strings.
Stefan
next prev parent reply other threads:[~2019-03-22 12:33 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-11 18:12 Oddities with dynamic modules Eli Zaretskii
2018-10-12 14:29 ` Kaushal Modi
2019-02-10 20:23 ` Philipp Stephani
2019-02-11 15:45 ` Eli Zaretskii
2019-02-11 16:04 ` Yuri Khan
2019-03-21 20:04 ` Philipp Stephani
2019-03-21 20:17 ` Eli Zaretskii
2019-03-21 20:32 ` Philipp Stephani
2019-03-21 20:46 ` Eli Zaretskii
2019-03-21 20:51 ` Philipp Stephani
2019-03-21 20:12 ` Philipp Stephani
2019-03-21 20:25 ` Eli Zaretskii
2019-03-21 20:34 ` Philipp Stephani
2019-03-21 20:51 ` Eli Zaretskii
2019-03-21 20:58 ` Philipp Stephani
2019-03-22 1:26 ` creating unibyte strings (was: Oddities with dynamic modules) Stefan Monnier
2019-03-22 7:41 ` Eli Zaretskii
2019-03-22 12:33 ` Stefan Monnier [this message]
2019-03-22 13:27 ` creating unibyte strings Eli Zaretskii
2019-03-22 14:23 ` Stefan Monnier
2019-03-22 15:11 ` Eli Zaretskii
2019-03-22 15:37 ` Stefan Monnier
2019-03-22 15:54 ` Eli Zaretskii
2019-03-24 14:51 ` Elias Mårtenson
2019-03-24 17:10 ` Eli Zaretskii
2019-03-25 1:47 ` Elias Mårtenson
2019-03-25 3:41 ` Eli Zaretskii
2019-03-26 10:23 ` Elias Mårtenson
2019-03-26 11:12 ` Stefan Monnier
2019-03-22 8:20 ` Oddities with dynamic modules Eli Zaretskii
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