From: "Neil Jerram" <neiljerram@googlemail.com>
To: hanwen@xs4all.nl
Cc: guile-devel@gnu.org
Subject: Re: Internal visibility
Date: Mon, 9 Jun 2008 19:10:23 +0100 [thread overview]
Message-ID: <49dd78620806091110v7a667787mef392fbf4446139d@mail.gmail.com> (raw)
In-Reply-To: <g1v0ji$3n1$1@ger.gmane.org>
2008/6/1 Han-Wen Nienhuys <hanwen@xs4all.nl>:
> const char* ptr = scm_i_string_chars(scmval);
> string x(ptr);
>
> is the most straightforward and efficient way to create a string.
> Using the API incurs an additional malloc, memcpy and free.
Does "string x(ptr)" incur a malloc and memcpy?
I assume it must do, or else the code above would be unsafe (sharing
memory between the C++ and SCM strings). So, assuming it does, why do
you think this is Guile's problem, and not C++'s?
To put it another way: can you use another form of C++ string
construction that does not do a malloc/memcpy itself, but takes
ownership of the char * that is passed to it? Then you could use this
together with scm_to_locale_string(), and you'd still only have one
malloc/memcpy overall.
Guile's string API is aiming not to be 8-bit-assuming, and I would
guess from the code above that the C++ string class is 8-bit-assuming.
Therefore, in the sequence
SCM -> char * -> string
it makes sense to have the malloc/memcpy between SCM and char *, not
between char * and string.
More generally, as regards cases where people are currently using
scm_i_string_chars(), I can imagine that there are good reasons why -
e.g. searching for a particular character or substring. But I think
we should be aiming to encapsulate those uses in new APIs that will
still work when Guile has non-8-bit strings.
Regards,
Neil
next prev parent reply other threads:[~2008-06-09 18:10 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-07 23:46 [PATCH] Fix continuation problems on IA64 Neil Jerram
2008-05-08 20:09 ` Ludovic Courtès
2008-05-08 21:29 ` Neil Jerram
2008-05-09 8:15 ` Ludovic Courtès
2008-05-09 22:19 ` Neil Jerram
2008-05-11 3:06 ` Ludovic Courtès
2008-05-12 21:02 ` Neil Jerram
2008-05-14 3:45 ` Internal visibility Ludovic Courtès
2008-05-27 21:32 ` Ludovic Courtès
2008-05-31 21:23 ` Ludovic Courtès
2008-06-01 8:00 ` Neil Jerram
2008-06-01 11:05 ` Ludovic Courtès
2008-06-01 20:48 ` Neil Jerram
2008-06-01 22:02 ` Ludovic Courtès
2008-06-01 20:24 ` Han-Wen Nienhuys
2008-06-09 18:10 ` Neil Jerram [this message]
2008-06-10 1:51 ` Han-Wen Nienhuys
2008-06-10 7:37 ` Ludovic Courtès
2008-06-10 8:04 ` Thien-Thi Nguyen
2008-06-10 12:09 ` Ludovic Courtès
2008-06-11 7:49 ` Thien-Thi Nguyen
2008-06-11 12:20 ` Ludovic Courtès
2008-06-12 20:45 ` Mike Gran
2008-06-23 12:20 ` Ludovic Courtès
2008-06-11 4:05 ` Han-Wen Nienhuys
2008-06-11 7:18 ` Ludovic Courtès
2008-06-11 7:24 ` Clinton Ebadi
2008-06-11 7:39 ` Ludovic Courtès
2008-06-11 16:09 ` Han-Wen Nienhuys
2008-06-23 12:18 ` Ludovic Courtès
2008-06-11 7:37 ` Neil Jerram
2008-05-12 22:18 ` [PATCH] Fix continuation problems on IA64 Neil Jerram
2008-05-14 2:55 ` Ludovic Courtès
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