gistfile1.rb

# When you have duplication like this

def base_price(options = {})
  PriceFormatter::Formatter.format(super, options)
end

def price(options = {})
  PriceFormatter::Formatter.format(base_price * quantity, options)
end

# You can change it into declarative style like this

formats_as_price :base_price, :price

def price
  base_price * quantity
end

# Much cleaner, but... Doesn't work in case of #price method above. 
# Even though all the standard attribute methods such as base_price get overridden, 
# my own defined #price method doesn't. Here's the plugin code. 

module Helper
  def self.included(base)
    base.extend(ClassMethods)
  end
    
  module ClassMethods
    def formats_as_price(*meths)
      meths.each do |meth|
        define_method meth do |*args|
          options = args.extract_options!
          PriceFormatter::Formatter.format(super, options)
        end
      end
    end
  end
end

ActiveRecord::Base.send(:include, PriceFormatter::Helper)