Ruby decorator pattern

gistfile1.rb

module Decorator
  def initialize(decorated)
    @decorated = decorated
  end

  def method_missing(method, *args)
    args.empty? ? @decorated.send(method) : @decorated.send(method, args)
  end
end

module Memoization
  def memo(name)
    @@lookup ||= Hash.new { |h, k| h[k] = {} }

    f = instance_method(name)

    define_method(name) do |args|
      return @@lookup[name][args] if @@lookup[name].include?(args)
      @@lookup[name][args] = f.bind(self).call(args)
    end
  end
end

module Memo
  def memo(name)
    @@cache = Hash.new
    f = instance_method(name)

    define_method(name) do |args|
      return @@cache[args] if @@cache.include? args
      @@cache[args] = f.bind(self).call(args)
    end
  end
end


class Calculator
  extend Memoization

  memo \
  def fact(n)
    return 1 if n <= 1
    n * fact(n-1)
  end

  memo \
  def fib(n)
    return 1 if n <= 1
    fib(n - 1) + fib(n - 2)
  end
end

class C2
  extend Memo

  memo \
  def fib(n)
    return 1 if n <= 1
    fib(n - 1) + fib(n - 2)
  end

  memo \
  def fact(n)
    return 1 if n <= 1
    n * fact(n - 1)
  end
end

t1 = Calculator.new
p t1.fact(20)
p t1.fib(20)
p Calculator.new.fact(20)
p Calculator.new.fib(35)
t = C2.new
p t.fact(35)
p t.fib(35)