A memory-leaking memoization implemenation inspired by https://twitter.com/PragTob/status/969292754294583297

memoize_example.rb

module Memo
  def memoize(method_name)
    original_method = instance_method(method_name)
    method_cache = Hash.new { |h, k| h[k] = {} }
    define_method(method_name) do |*args, &block|
      if method_cache[self].key?([args, block])
        method_cache[self][[args, block]]
      else
        method_cache[self][[args, block]] = original_method.bind(self).call(*args, &block)
      end
    end
  end

end

class Count
  FOO = (1..Float::INFINITY).each.lazy
  def count
    FOO.next
  end
  extend Memo
  memoize :count
end