Memoize solutions

gistfile1.rb

# Solution 1:

class Memoizer < BasicObject
  def initialize(instance)
    @instance = instance
    @cache = {}
  end

  def cache(method, *args)
    @cache["#{method}, #{args}"] = @instance.public_send method, *args
  end

  def memoize(method, *args)
    @cache["#{method}, #{args}"] || cache(method, *args)
  end

  def method_missing(method, *args, &block)
    if ::Kernel.send :block_given?
      return @instance.public_send method, *args, &block
    else
      memoize method, *args
    end
  end

  private :cache, :memoize
end

# Solution 2:

class Memoizer < BasicObject
  def initialize(target)
    @target = target
    @cache = {}
  end

  def method_missing(method, *args, &block)
    if @target.respond_to? method
      key = "#{method}, #{args}"
      return @cache[key] if @cache.has_key? key
      value = @target.public_send method, *args, &block
      block.nil? ? @cache[key] = value : value
    else
      ::Kernel.raise ::NoMethodError
    end
  end
end