From: Masaya TARUI <tarui@...>
Date: 2010-07-09T19:48:03+09:00
Subject: [ruby-core:31152] Re: Why is there no standard way of creating a 	String from a char *?

It is not guaranteed that Ruby uses existing malloc.
I think that you can use DL:CPtr for your purpose.


2010/7/9 Nikolai Weibull <now@bitwi.se>:
> On Fri, Jul 9, 2010 at 06:20, Urabe Shyouhei <shyouhei@ruby-lang.org> wrote:
>> (2010/07/09 7:04), Nikolai Weibull wrote:
>
>>> Why is there no standard way of creating a String from a char *?  All
>>> the rb_str_new* functions take a const char * and copy it.  I would
>>> like a function that would create a String from a char *, that is,
>>> without copying it.
>
>> Because there is GC.  You can't say if a string content should be freed or not
>> when you allow such creation.  If you need a non-copying region of a memory
>> that should not be called a String.
>
> Perhaps I was unclear in my problem description.  If I have a freshly
> allocated char * that I get from a library call, why shouldn’t I be
> able to use it as the basis of a Ruby String?  I mean, currently I
> have to do
>
> int length;
> char *result = library_call(…, &length, …);
> VALUE rbresult = rb_str_new(result, length);
> free(result);
> return rbresult;
>
> I own result, so after creating rbresult I currently have to
> immediately free it.  I realize that this doesn’t really matter at all
> for small strings, but say that library_call() returns the contents of
> an arbitrarily large file.  Copying result inside rb_str_new seems to
> me to be a total waste of energy.
>
>



-- 
樽家昌也(Masaya TARUI)
No Tool,No Life.