From: ts <decoux@...>
Date: 2002-04-23T02:12:30+09:00
Subject: Re: newbie embedding

>>>>> "J" == Jamie Knight <bigjim16@btinternet.com> writes:

J> class A
J>   def test()
J>     puts "rah"
J>   end
J> end

J> and the following c:

J> #include "ruby.h"

J> void main()
J> {
J>  VALUE classy;
J>  ID function;

J>  ruby_init();

J>  ruby_script("embedded");
J>  rb_load_file("test.rb");

J>  classy=rb_const_get(rb_cObject,rb_intern("A"));
J>  function=rb_intern("test");
J>  rb_funcall(classy,function,0);
J> }

 You have 2 errors :

   1) rb_load_file() compile the file but don't execute the nodes
   2) you are trying to call a *class* method (i.e. the receiver is classy,
      the class) and in test.rb you have defined an *instance* method


 Write it like this :

pigeon% cat test.rb
class A
  def test()
    puts "rah"
  end
end
pigeon% 

pigeon% cat aa.c
#include "ruby.h"

int main()
{
    VALUE classy, obj;
    ID function;

    ruby_init();
    ruby_script("embedded");
    rb_load(rb_str_new2("test.rb"), 0);

    classy = rb_const_get(rb_cObject,rb_intern("A"));
    obj = rb_funcall(classy, rb_intern("new"), 0);
    function = rb_intern("test");
    rb_funcall(obj,function,0);
    return 0;
}

pigeon% 

pigeon% aa
rah
pigeon% 

 First you call A.new to have an object, then you call the instance method
 of this object.

 There is a problem with my script. If ruby don't find "test.rb" it will
 call rb_raise() and this will crash your program, because you have not
 protected the call to rb_load()

 You can use rb_protect() for this something like this :

pigeon% cat aa.c
#include "ruby.h"

VALUE call_test()
{
    VALUE classy, obj;
    ID function;

    rb_load(rb_str_new2("test.rb"), 0);

    classy = rb_const_get(rb_cObject,rb_intern("A"));
    obj = rb_funcall(classy, rb_intern("new"), 0);
    function = rb_intern("test");
    rb_funcall(obj,function,0);
    return Qnil;
}

int main()
{
    int error = 0;

    ruby_init();
    ruby_script("embedded");
    rb_protect(call_test, 0, &error);
    if (error) {
        VALUE mes = rb_inspect(rb_gv_get("$!"));
        fprintf(stderr, "ERROR : %s\n", RSTRING(mes)->ptr);
        return 1;
    }
    return 0;
}

pigeon% 

pigeon% rm test.rb
pigeon%
 
pigeon% aa
ERROR : #<LoadError: No such file to load -- test.rb>
pigeon% 



Guy Decoux