Ruby Object Configuration Block

irb.rb

1.9.2p290 :083 > MyObject.configure do |config|
1.9.2p290 :084 >     config.logger = STDOUT
1.9.2p290 :085?> end
 => MyObject 
1.9.2p290 :190 > MyObject.new
 => #<MyObject:0x000001009ae268 @logger=#<IO:<STDOUT>>> 
1.9.2p290 :191 > MyObject.new(:logger => nil)
 => #<MyObject:0x000001009a6928 @logger=nil> 

my_object.2.rb

class MyObject
  VALID_ATTRIBUTE_KEYS = [:logger]

  def initialize(attributes={})
     attributes = MyObject.config.merge(attributes)
     MyObject::VALID_ATTRIBUTE_KEYS.each do |key|
       instance_variable_set("@#{key}", attributes[key])
     end
  end

  class << self
    attr_accessor :logger

    def configure
      yield self

      self
    end

    def defaults
      {:logger => nil}
    end
   
    def config
      attributes = defaults
      VALID_ATTRIBUTE_KEYS.each do |key| 
        attributes[key] = send(key) if send(key)
      end

      attributes
    end
  end
end