From: "Brett W. Denner" <Brett.W.Denner@...>
Date: 2001-07-13T02:07:47+09:00
Subject: [ruby-talk:17740] Ruby/C extension for module with nested classes

I am trying to create a Ruby extension that consists of a module containing
several classes.  In my example, the module is called Fruit, and one of the
classes is Apple.  I would like use the module as follows:

    	require 'Fruit'
    	a = Fruit::Apple.new

If I wanted to write the module and classes in Ruby, it would look like
this:

	module Fruit
	class Apple
	  def initialize
	  end
	end
	end

In my efforts to create an extension using C, my extconf.rb file looks like
this:

	require 'mkmf'
	create_makefile('Fruit')

and the C source file (called fruit.c) looks like this:

	#include "ruby.h"
	#include <stdio.h>

	static VALUE s_init(VALUE self) { return self; }

	VALUE cFruit;

	void Init_Fruit() {
	    cFruit = rb_define_module("Fruit");
	    fprintf(stderr, "Init_Fruit\n");
	}

	VALUE cApple;

	void Init_Apple() {
	    cApple = rb_define_class_under(cFruit, "Apple", rb_cObject);
	    rb_define_method(cApple, "initialize", s_init, 0);
	    fprintf(stderr, "Init_Apple\n");
	}

When I run "ruby extconf.rb" and "make", everything compiles just fine. 
However, when I try to use the
module (using the sample Ruby code at the top) I get the following output:

	Init_Fruit
	./test.rb:4: uninitialized constant Apple at Fruit (NameError)

I realize that the Fruit::Apple.new syntax could be incorrect, but I've
tried  Fruit#Apple and Fruit.Apple, but
nothing works.  In each case, the Init_Apple subroutine is not being called.

How do I modify my code to create an extension with for a module with nested
classes?

Thanks,

Brett Denner



-- 
 Brett W. Denner                    Lockheed Martin Aeronautics Co.
 email: Brett.W.Denner@lmco.com     PO Box 748, MZ 9332
 phone: 817-935-1144                Fort Worth, TX 76101
 fax:   817-935-1212