From: John Platte <john.platte@...>
Date: 2004-04-17T07:32:07+09:00
Subject: Class instance method can't be defined in a module?

Trying to work some attr_accessor - style magic so I can refactor a 
bunch of menial methods into a single declaration. Can't subclass, so 
I'm trying to do it with a module.

In the code below, I expect both of the "puts" lines to work on the 
"abc" string, but I can't figure out what I'm missing. Can anyone 
enlighten me here?

module FooModule
   def delegate(*methods)
     methods.each {|method|
       module_eval %{
         def #{method}
           @new_receiver.#{method}
         end
       }
     }
   end
   module_function :delegate
end

class TryIt
   include FooModule
   FooModule.delegate :intern
   delegate :capitalize
   def initialize(obj)
     @new_receiver = obj
   end
end

t = TryIt.new("abc")
puts t.intern
puts t.capitalize

=====
$ ruby demo.rb
demo.rb:17: undefined method `delegate' for TryIt:Class (NoMethodError)

(now comment out the line "delegate :capitalize")

$ ruby demo.rb
abc
demo.rb:25: undefined method `capitalize' for #<TryIt:0x283c8 
@new_receiver="abc"> (NoMethodError)

-- 
Ryan "John" Platte
Custom services, NIKA Consulting
http://nikaconsulting.com/