From: "Mauricio Fernández" <batsman.geo@...>
Date: 2003-07-07T02:03:42+09:00
Subject: Re: Help with UnboundMethod#bind error

On Sun, Jul 06, 2003 at 11:51:04PM +0900, Pit Capitain wrote:
> On 6 Jul 2003 at 21:23, ts wrote:
> 
> > >>>>> "P" == Pit Capitain <pit@capitain.de> writes:
> > 
> > P> yes, I know that you hacked Ruby and that Matz is also working on it, 
> > P> but for me using the PragProg Ruby installer on Windows nothing of 
> > P> those I can use right now.
> > 
> >  Write an extension :
> > 
> > (... demo of Guy's secret code in action ...)
> 
> This is the real Guy Decoux we all love and respect!
> 
> I know you can do it and maybe I would be able to do so, too, after 
> spending enough time on it. Thank you for trying to motivate me to 
> come up with my own solution. But I'm sure this won't happen. So I'll 
> be waiting for Matz's code. Maybe Nobu will find some time to tell me 
> why my pure Ruby solution doesn't work.

The extension is easy to write (although you'll have to wait for Guy to
check if my code is a time bomb :-):

override.c:
===================
#include <ruby.h>
#include <st.h>
#include <node.h>


static
VALUE
class_override(VALUE self, VALUE symbols)
{
 int len;
 int i;
 VALUE meth;
 VALUE name;
 st_data_t data;

 NEWOBJ(proxy, struct RClass);
 OBJSETUP(proxy, rb_cClass, T_ICLASS);

 len = RARRAY(symbols)->len;

 proxy->iv_tbl = st_init_numtable(); /* not needed? */
 proxy->m_tbl = st_init_numtable();
 proxy->super = RCLASS(self)->super;

 RBASIC(proxy)->klass = RBASIC(self)->klass;

 for(i = 0; i < len; i++) {
         meth = rb_ary_entry(symbols, i);
         name = rb_funcall(meth, rb_intern("to_s"), 0);
         if(!st_lookup(RCLASS(self)->m_tbl, rb_intern(RSTRING(name)->ptr), &data))
                 continue; /* should do something else?? */
         st_insert(proxy->m_tbl, rb_intern(RSTRING(name)->ptr), data);
 }

 RCLASS(self)->super = proxy;
 OBJ_INFECT(proxy, self);

 return self;
}


void
Init_override()
{
  rb_define_method(rb_cClass, "override", class_override, -2);
}
===================

extconf.rb:
===================
require 'mkmf'
create_makefile("override")
===================


And then...

batsman@tux-chan:~/src/override$ expand -t2 b.rb
#!/usr/bin/ruby
require 'override'

class C
   def m
      puts "original"
   end
end

C.new.m  # => original

class C
   override :m
   def m
      puts "before(1)"
      super
   end
end

C.new.m  # => before(1), original

class C
   override :m
   def m
      puts "before(2)"
      super
   end
end

C.new.m  # => before(2), before(1), original
batsman@tux-chan:~/src/override$ ruby b.rb
original
b.rb:14: warning: method redefined; discarding old m
before(1)
original
b.rb:24: warning: method redefined; discarding old m
before(2)
before(1)
original

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batsman dot geo at yahoo dot com

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