* Re: decode-coding-string and consing
[not found] <mailman.1774.1044945196.21513.help-gnu-emacs@gnu.org>
@ 2003-02-11 17:26 ` Jesper Harder
0 siblings, 0 replies; 5+ messages in thread
From: Jesper Harder @ 2003-02-11 17:26 UTC (permalink / raw)
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.
^ permalink raw reply [flat|nested] 5+ messages in thread
* decode-coding-string and consing
@ 2003-02-10 16:47 Jesper Harder
2003-02-10 20:01 ` Eli Zaretskii
[not found] ` <mailman.1748.1044907500.21513.help-gnu-emacs@gnu.org>
0 siblings, 2 replies; 5+ messages in thread
From: Jesper Harder @ 2003-02-10 16:47 UTC (permalink / raw)
,----[ C-h f decode-coding-string RET ]
| decode-coding-string is a built-in function.
| (decode-coding-string STRING CODING-SYSTEM &optional NOCOPY)
|
| Decode STRING which is encoded in CODING-SYSTEM, and return the result.
| Optional arg NOCOPY non-nil means it is OK to return STRING itself
| if the decoding operation is trivial.
`----
Under what conditions is the decoding operation "trivial"?
I was hoping that something like:
(decode-coding-string "abc" 'us-ascii t) or
(decode-coding-string "abc" 'latin-1 t)
wouldn't cons a new string; but unfortunaley it does.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: decode-coding-string and consing
2003-02-10 16:47 Jesper Harder
@ 2003-02-10 20:01 ` Eli Zaretskii
[not found] ` <mailman.1748.1044907500.21513.help-gnu-emacs@gnu.org>
1 sibling, 0 replies; 5+ messages in thread
From: Eli Zaretskii @ 2003-02-10 20:01 UTC (permalink / raw)
> Newsgroups: gnu.emacs.help
> From: Jesper Harder <harder@myrealbox.com>
> Date: Mon, 10 Feb 2003 17:47:53 +0100
>
> ,----[ C-h f decode-coding-string RET ]
> | decode-coding-string is a built-in function.
> | (decode-coding-string STRING CODING-SYSTEM &optional NOCOPY)
> |
> | Decode STRING which is encoded in CODING-SYSTEM, and return the result.
> | Optional arg NOCOPY non-nil means it is OK to return STRING itself
> | if the decoding operation is trivial.
> `----
>
> Under what conditions is the decoding operation "trivial"?
If CODING-SYSTEM is nil or such that no encoding is necessary at all.
^ permalink raw reply [flat|nested] 5+ messages in thread
[parent not found: <mailman.1748.1044907500.21513.help-gnu-emacs@gnu.org>]
* Re: decode-coding-string and consing
[not found] ` <mailman.1748.1044907500.21513.help-gnu-emacs@gnu.org>
@ 2003-02-10 21:53 ` Jesper Harder
2003-02-11 6:32 ` Eli Zaretskii
0 siblings, 1 reply; 5+ messages in thread
From: Jesper Harder @ 2003-02-10 21:53 UTC (permalink / raw)
"Eli Zaretskii" <eliz@is.elta.co.il> writes:
>> ,----[ C-h f decode-coding-string RET ]
>> | decode-coding-string is a built-in function.
>> | (decode-coding-string STRING CODING-SYSTEM &optional NOCOPY)
>> |
>> | Decode STRING which is encoded in CODING-SYSTEM, and return the result.
>> | Optional arg NOCOPY non-nil means it is OK to return STRING itself
>> | if the decoding operation is trivial.
>> `----
>>
>> Under what conditions is the decoding operation "trivial"?
>
> 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)
The input string and the output string are identical. Why is it
necessary to cons a new string here?
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: decode-coding-string and consing
2003-02-10 21:53 ` Jesper Harder
@ 2003-02-11 6:32 ` Eli Zaretskii
0 siblings, 0 replies; 5+ messages in thread
From: Eli Zaretskii @ 2003-02-11 6:32 UTC (permalink / raw)
On Mon, 10 Feb 2003, Jesper Harder wrote:
> >> Under what conditions is the decoding operation "trivial"?
> >
> > 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 not really a coding system.
Why not nil or raw-text?
Anyway, is there some real problem behind this discussion?
^ permalink raw reply [flat|nested] 5+ messages in thread
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2003-02-11 17:26 ` decode-coding-string and consing Jesper Harder
2003-02-10 16:47 Jesper Harder
2003-02-10 20:01 ` Eli Zaretskii
[not found] ` <mailman.1748.1044907500.21513.help-gnu-emacs@gnu.org>
2003-02-10 21:53 ` Jesper Harder
2003-02-11 6:32 ` Eli Zaretskii
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