From: Charles Oliver Nutter <charles.nutter@...>
Date: 2009-01-19T06:32:17+09:00
Subject: [ruby-core:21422] Re: Proposal: Module#copy_method

Yehuda Katz wrote:
> I'd like it to be possible to copy methods from one module to another. 
> The rationale is that this feature would make it possible to modify 
> existing methods without being forced to resort to aliasing. Here's an 
> implementation that works on 1.8 and 1.9:

Here's a pure-ruby version that works on an unmodified JRuby:

require 'jruby'

class Module
   def copy_method(mod, sym)
     # get JRuby DynamicMethod object from RubyMethod
     org.jruby.RubyMethod.field_reader :method
     ruby_method = mod.instance_method(sym)
     real_method = JRuby.reference(ruby_method).method

     # native methods may have memory/object layout needs
     raise "can't copy native method" if real_method.native?

     # Add it directly to the JRuby RubyModule self
     real_modcls = JRuby.reference(self)
     real_modcls.add_method(sym.to_s, real_method)
   end
end

- Charlie