Re: How to get buffer byte length (not number of characters)?

[Joseph Turner <joseph@ushin.org>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Joseph Turner <joseph@ushin.org>
>> Cc: emacs-devel@gnu.org,  schwab@suse.de,  adam@alphapapa.net
>> Date: Fri, 23 Aug 2024 00:43:52 -0700
>> 
>> I'm surprised that
>> 
>> (with-temp-buffer
>>   (insert "你好")
>>   (set-buffer-file-coding-system 'chinese-big5)
>>   (car (find-coding-systems-region (point-min) (point-max))))
>> 
>> returns 'utf-8 and not 'chinese-big5.
>
> What does coding-system-priority-list returns in your case?

'utf-8

>> Are the codings intended to be
>> ordered by priority?
>
> Yes.
>
>> If so, should buffer-file-coding-system be at the front of the list
>> if it's safe?
>
> How do you know it's safe?
>
> If your application needs to prefer buffer-file-coding-system, then
> you should see if buffer-file-coding-system is a member of the list
> returned by find-coding-systems-region, and if so, use that.

I'd have thought that most applications would want to prefer
buffer-file-coding-system if it's a member of the list returned by
find-coding-systems-region, but perhaps not.

I now have a clear path forward for hyperdrive.el.

Thank you for your time, Eli!!

Joseph