From: nobu.nokada@...
Date: 2001-11-19T10:55:14+09:00
Subject: [ruby-talk:25807] Re: Subclassing native struct oddity

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At Mon, 19 Nov 2001 06:16:09 +0900,
Kero van Gelder <kero@d4050.upc-d.chello.nl> wrote:
> [2 native.c <text/x-csrc; us-ascii (7bit)>]
> #include <ruby.h>
> 
> VALUE rb_cBla;
> 
> VALUE bla_new(VALUE module) {
>   int *b = ALLOC(int);
>   VALUE bla;
>   *b = 7;
>   bla = Data_Wrap_Struct(rb_cBla, NULL, free, b);
>   return bla;
> }

You'd better to define Bla#initialize not but Bla.new only, or
Blaat#initialize would never be called.


> void Init_native(void) {
>   rb_cBla = rb_define_class("Bla", rb_cObject);
>   rb_define_module_function(rb_cBla, "new", bla_new, 0);
> }

And bla_new() shouldn't be a module function but a singleton
method.  Of course, as David wrote, hardcoded rb_cBla is the
problem.


With 1.7 feature, new allocation framework, see attachments.



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#include <ruby.h>

VALUE rb_cBla;

#if HAVE_OBJECT_ALLOCATE
static VALUE
bla_allocate(VALUE klass)
{
    return Data_Wrap_Struct(klass, NULL, free, ALLOC(int));
}
#else
static VALUE
bla_new(int argc, VALUE *argv, VALUE klass)
{
    VALUE bla = Data_Wrap_Struct(klass, NULL, free, ALLOC(int));
    rb_obj_call_init(bla, argc, argv);
    return bla;
}
#endif

static VALUE
bla_initialize(VALUE bla)
{
    int *b;
    Data_Get_Struct(bla, int, b);
    *b = 7;
    return bla;
}

void
Init_native(void)
{
    rb_cBla = rb_define_class("Bla", rb_cObject);
#if HAVE_OBJECT_ALLOCATE
    rb_define_singleton_method(rb_cBla, "allocate", bla_allocate, 0);
#else
    rb_define_singleton_method(rb_cBla, "new", bla_new, -1);
#endif
    rb_define_method(rb_cBla, "initialize", bla_initialize, 0);
}

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require 'mkmf'
$CPPFLAGS += " -DHAVE_OBJECT_ALLOCATE" if Object.respond_to? :allocate
create_makefile("native")

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Nobu Nakada

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