Caching decorator in ruby 2.1

caching_decorator.rb

# In ruby 2.1, the method definition returns the name of the method. As a
# result, python-decorator-like class methods can be created.
#

module CachingDecorator
  def cached(method_name)
    alias_method("_generate_#{method_name}", method_name)

    define_method(method_name) do
      @_caching_decorator_cache ||= {}

      if not @_caching_decorator_cache.key?(method_name)
        @_caching_decorator_cache[method_name] = method("_generate_#{method_name}").call
      end

      @_caching_decorator_cache[method_name]
    end

    # Return the method name, so we could chain decorators
    method_name
  end
end

# As example usage, a stupid wrapper around net/http

require 'net/http'

class Http
  extend CachingDecorator

  def initialize(url)
    @url = url
  end

  def body
    response.body
  end

  def headers
    response.to_hash
  end

  # We could do this:
  #
  #   private
  #
  #   def response
  #     @response ||= Net::HTTP.get_response(URI(@url))
  #   end
  #

  # But, we could also:
  private cached def response
    uri = URI(@url)
    Net::HTTP.get_response(uri)
  end
end

rubygems = Http.new('http://rubygems.org')

puts "Headers:"
puts rubygems.headers

puts "Body:"
puts rubygems.body[0..50].inspect