gistfile1.txt

module Memoizer
  def method_added(meth)
    @_methods_to_memoize ||= []
    @_methods_to_memoize << meth
  end
  
  def methods_to_memoize
    @_methods_to_memoize
  end
end
 
class Class
  def memoize(kind = Hash, &blk)
    memoizer = Module.new do
      extend Memoizer
    end
    
    memoizer.class_eval(&blk)
    self.send(:include, memoizer)
    
    memoizer.methods_to_memoize.each do |meth|
      arity = self.instance_method(meth).arity
      if arity == 0
        self.class_eval <<-RUBY
def #{meth}
@_memoized_#{meth} ||= super
end
RUBY
      else
        args = arity == 1 ? "args" : "*args"
        self.class_eval <<-RUBY
def #{meth}(#{args})
@_memoized_#{meth} ||= #{kind}.new
@_memoized_#{meth}[args] ||= super
end
RUBY
      end
    end
  end
end

class Foo
  class << self
    memoize do
      def memoed(baz)
        baz * 1000
      end
    end

	  def unmemoed(baz)
      baz * 1000
	  end
  end
  
  def self.baseline(baz)
    baz * 1000
  end
  
  memoize do
    def memoed(baz)
      baz * 1000
    end
  end
  
  def unmemoed(baz)
    baz * 1000
  end
end

require 'benchmark'
n = 500
arr = [1,10,100,1000,10000]
Benchmark.bm do |x|
  arr.each do |m|
   x.report { n.times{Foo.memoed(m)} }
   x.report { n.times{Foo.unmemoed(m)}}
   x.report { n.times{Foo.baseline(m)}}
   a_foo = Foo.new
   x.report { n.times{a_foo.memoed(m)} }
   x.report { n.times{a_foo.unmemoed(m)} }
   puts "-----------------------------"
 end
end