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Re: decode-coding-string and consing
From: |
Jesper Harder |
Subject: |
Re: decode-coding-string and consing |
Date: |
Tue, 11 Feb 2003 18:26:36 +0100 |
User-agent: |
Gnus/5.090016 (Oort Gnus v0.16) Emacs/21.3.50 |
Eli Zaretskii <eliz@is.elta.co.il> writes:
> On Mon, 10 Feb 2003, Jesper Harder wrote:
>
>> > If CODING-SYSTEM is nil or such that no encoding is necessary at
>> > all.
>>
>> But I don't understand why any encoding is needed at all in:
>>
>> (decode-coding-string "abc" 'us-ascii t)
>
> Why did you use us-ascii at all here?
It's just as an example where it's obvious that no encoding is needed.
What I'm really interested in is:
(decode-coding-string "abc" 'latin-1 t)
i.e. decoding a pure ASCII string as latin-1 (or another strict superset
of ASCII).
This pseudo-code for what I'd like to do efficiently:
,----
| (defun my-decode-coding-string (string coding-system nocopy)
| (if (and nocopy
| (STRING has no 8bit chars)
| (CODING-SYSTEM is a superset of ascii))
| string
| (decode-coding-string string coding-system nocopy)))
`----
> Anyway, is there some real problem behind this discussion?
Yes. Gnus conses excessively.
If `decode-coding-string' was a bit more clever about not consing a
string when it's not strictly necessary, we could cons ~ 2*N less
strings when constructing a summary buffer (N = number of articles).
It's also an issue when constructing a server buffer, where N is usually
large -- i.e. ~ 50.000-100.000 unnecessary strings are consed.
- Re: decode-coding-string and consing,
Jesper Harder <=