From: Gyoung-Yoon Noh <nohmad@...>
Date: 2005-11-13T19:01:31+09:00
Subject: Re: More fun with C

On 11/13/05, Eric Hofreiter <erichof425@yahoo.com> wrote:
> I really wasn't trying to complain, I just wanted a little help, and I guess I got carried away since I was frustrated and confused.  Reading it over again I realize that I sounded stupid.  But you people seem to have a lot of free time to pick apart everything that I say.  Sorry for wasting it.
>
> Back to the point: can anyone tell me how to use rb_require or rb_const_get?  I get errors when I use them like so: rb_require("myfile"); rb_const_get(rb_cObject, rb_intern("MyClass")).  Is there another way to load a file or get a user-defined class name?  Thank you for any helpful responses.
>
> >Eric Hofreiter just won't give up:
> [snip]
> >daz
>
>
> ---------------------------------
>  Yahoo! FareChase - Search multiple travel sites in one click.
>

* rb_require("myfile") is exactly same as Kernel.require "myfile".
* rb_const_get(rb_cObject, rb_intern("MyClass")) is exactly same as
Object.const_get("MyClass").


$ cat extconf.rb
require 'mkmf'
create_makefile 'example'

$ cat example.c
#include "ruby.h"

VALUE
example_get_class(VALUE self, VALUE str)
{
    return rb_const_get(rb_cObject, rb_intern(RSTRING(str)->ptr));
}

void
Init_example(void)
{
    rb_require("set");
    rb_define_global_function("get_class", example_get_class, 1);
}

$ make
i686-pc-linux-gnu-gcc -fPIC -O2 -march=athlon-xp -pipe  -fPIC  -I.
-I/usr/lib/ruby/1.8/i686-linux -I/usr/lib/ruby/1.8/i686-linux -I.   -c
example.c
i686-pc-linux-gnu-gcc -shared  -L'/usr/lib' -Wl,-R'/usr/lib' -o
example.so example.o  -Wl,-R -Wl,/usr/lib -L/usr/lib -L. -lruby18 
-ldl -lcrypt -lm   -lc

$ irb -f
irb(main):001:0> require 'example'  #=> 'set' loaded
=> true
irb(main):002:0> Set == Object.const_get("Set")
=> true
irb(main):003:0> Set == get_class("Set")
=> true


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