fast_value_object.rb

gistfile1.txt

  module ValueObject
    def self.included(klass)
      klass.extend(ClassMethods)
      klass.attributes # Force instantiation
    end

    def initialize(data)
      data.each do |key, value|
        instance_variable_set("@#{key}", value)
      end
    end

    def ==(other)
      equality_key == other.equality_key
    end

    def eql?(other)
      equality_key.eql?(other.equality_key)
    end

    def hash
      equality_key.hash
    end

    def equality_key
      self.class.attributes.map {|key, _|
        send(key)
      }
    end

    def inspect
      keyvalues = self.class.attributes.map {|key, _|
        "#{key}=#{send(key).inspect}"
      }.join(" ")

      "<#{self.class.name} #{keyvalues}>"
    end

    def to_s
      inspect
    end

    module ClassMethods
      def values(&block)
        instance_eval(&block)
      end

      def attributes
        @attributes ||= {}
      end

      def attribute(name, type = Object)
        attributes[name] = type

        define_method(name) do
          instance_variable_get("@#{name}")
        end
      end
    end
  end