class PropKey
  class << self # Class methods
    def resource_id
      "5"
    end
    def type
      "2"
    end
    def creation_date
      "2005-03-02"
    end
    def getlastmodified
      "2006-10-03"
    end
    def displayname
      "test object"
    end
    def resourcetype
      "file"
    end
    def owner
      "mnutt"
    end
    def getcontenttype
      "text/html"
    end
    #Media property
    def getcontentlength
      42
    end
  end
end

module Properties

  # Define properties that are shared by all resources.
  unless(const_defined?('DEFAULT_PROPERTIES'))
    DEFAULT_PROPERTIES = {:resource_id   => {:key => PropKey.resource_id},
                          :type          => {:key => PropKey.type},
                          :creation_date => {:key => PropKey.creation_date},
                          :last_modified => {:key => PropKey.getlastmodified},
                          :display_name  => {:key => PropKey.displayname},
                          :resource_type => {:key => PropKey.resourcetype},
                          :owner         => {:key => PropKey.owner},
                          :content_type  => {:key => PropKey.getcontenttype}}
  end

  # Setup class instance variables. These are filled out by the
  # define_properties call right after the class methods definition.
  @property_names = {}
  @protected_properties = []

  module ClassMethods

    attr_accessor :property_names

    # Defines valid properties for this class
    #
    def define_properties(props = {})
      props.each do |name, attr|
        module_eval <<-"end;"
          self.property_names[:#{name}] = attr[:key]

          def #{name}=(value)
            @properties[:#{name}] = value
          end

          def #{name}
            @properties[:#{name}]
          end

        end;
      end
    end

  end # End ClassMethods module

  extend ClassMethods

  # Add the class methods to the model it is being mixed into
  def self.append_features(klass)
  	super
  	klass.extend(ClassMethods)
  end

  self.define_properties(DEFAULT_PROPERTIES)

end

class Media
	include Properties

  define_properties :content_length => {:key => PropKey.getcontentlength}

end

# ==============================================================
# Error:
# NoMethodError: undefined method `[]=' for nil:NilClass
#        from ./mixins.rb:74:in `define_properties'
#        from ./mixins.rb:73:in `define_properties'
#        from ./mixins.rb:104
#        from (irb):1