Edx Class 169.1x HW 1-5

Advanced_oop.rb

#!/usr/bin/env ruby

class Class
    def attr_accessor_with_history(attr_name)
        attr_name = attr_name.to_s       # make sure it's a string
        attr_reader attr_name            # create the attribute's getter
        attr_reader attr_name+"_history" # create bar_history getter
        class_eval %Q"
            def #{attr_name}=(value)
                if !defined? @#{attr_name}_history
                    @#{attr_name}_history = [@#{attr_name}]
                end
                @#{attr_name} = value
                @#{attr_name}_history << value
            end
        "
    end
end

class Foo
    attr_accessor_with_history :bar
end