From: Daniel Schierbeck <daniel.schierbeck@...>
Date: 2005-11-15T00:22:16+09:00
Subject: Comparing Proc Objects?

Just for the laugh of it (I've got the flu) I wrote a little Cache Proxy 
class. Basically, when you call a method on the proxyed object it checks 
if that method has been called with the same arguments before. If that's 
the case, it returns the cached return value. What I'm interested in 
knowing is how I check whether any supplied block matches the one from 
the cached call.

This is my code:

   class EmptyClass
     instance_methods(true).each do |method|
       undef_method(method) unless ["__send__", "__id__"].include? method
     end
   end

   class Proxy < EmptyClass
     def initialize(obj)
       @obj = obj
     end

     def method_missing(name, *args, &block)
       @obj.send(name, *args, &block)
     end
   end

   class CacheProxy < Proxy
     def initialize(obj)
       @calls = []
       @obj = obj
     end

     def method_missing(name, *args, &block)
       call = MethodCall.new(name, *args, &block)
       if @calls.include? call
         return @calls.detect do |cached_call|
           cached_call == call
         end.return_value
       else
         call.return_value = return_value = super
         @calls << call
         return return_value
       end
     end

     class MethodCall
       include Comparable

       attr_reader :name, :args, :block
       attr_accessor :return_value

       def initialize(name, *args, &block)
         @name, @args, @block = name, args, block
       end

       def <=> (other)
         self.name <=> other.name
       end

       def == (other)
         self.name  == other.name and self.args  == other.args
       end
     end
   end


I bet this has already been done, and probably in a more efficient way, 
but hey, I'm bored...


Cheers,
Daniel