jays presenter pattern

gistfile1.rb

# from: http://pastie.org/47453
# http://blog.jayfields.com/2007/03/rails-presenter-pattern.html

class CompletePresenter < Presenter

  presentable :account, UserAccount.new
  presentable :address, Address.new
  presentable :credential, UserCredential.new

  def save
    account.save && address.save && credential.save
  end
  
end

class Presenter
  def initialize(params)
    params.each_pair { |attribute, value| self.send :"#{attribute}=", value } unless params.nil?
  end

  def self.presentable(name, instance)
    presentables[name.to_sym] = instance
    define_method name do
      instance
    end
  end
  
  def self.presentables
    @presentables ||= {}
  end
  
  def method_missing(sym, *args)
    super unless presentable?(sym)
    receiver, message = parse_method(sym)
    receiver.send message, *args
  end
  
  def presentable?(method_name)
    self.class.presentables.has_key? method_name.to_s.split("_").first.to_sym
  end
  
  def parse_method(method_name)
    receiver_key, *method_to_call_parts = method_name.to_s.split("_")
    [self.class.presentables[receiver_key.to_sym], method_to_call_parts.join("_").to_sym]
  end
end