Attribute Observers

attribute_observers.rb

module ProofTest
  class Model
    def self.attr_reader property
      define_method property do
        puts "reading #{attributes[property]} from #{property}"
        attributes[property]
      end
    end

    def self.attr_writer property
      define_method :"#{property}=" do |value|
        attributes[property] = value
        puts "setting #{property} to #{value}"
      end
    end

    def self.attr_accessor property
      attr_reader property
      attr_writer property
    end
    
    def attributes
      class << self
        @attributes ||= Hash.new
      end
    end
  end
end

module ProofTest
  class Person < Model
    attr_accessor :age
    attr_accessor :name
  end
end

david = ProofTest::Person.new

david.name = "David"
david.age = 25

p david

p david.attributes
david.attributes.each do |attribute, value|
  puts "Attribute #{attribute} is set to #{value}"
end