Ruby object extension for use with HAML

object.rb

# Easily add id and class attributes to HAML elements
# 
# %li{ account.element.to_hash } ->
# <li class='account' id='account-7'>
#
# %span{ account.element.button.to_hash } ->
# <span class='account-button' id='account-7-button'>
#
# %span{ :class => account.element.save.button.class } ->
# <span class='account-save-button'>
#
# %span{ :id => account.element.save.button }
# <span id='account-7-save-button'>
# 

class Object
  class Extendable < String
    def initialize object, parts = []
      @object, @parts = [object, parts.clone]
      replace parts.insert(0, object.class.name.demodulize.downcase.dasherize).join('-')
    end
    
    def class
      Extendable.new @object, @parts[1..-1].to_a
    end
    
    def to_hash
      { 
        :class  => self.class, 
        :id     => self
      }
    end
    
    private 
      def method_missing symbol, *args
        Extendable.new @object, @parts.push(symbol.to_s)
      end
  end
    
  def element
    if respond_to?(:to_param)
      Extendable.new(self, [to_param])
    elsif respond_to?(:key)
      Extendable.new(self, [key])
    else
      Extendable.new self
    end
  end
end