Simple ruby decorators with example

decorator_clone.rb

class DecoratorClone
  def initialize(model)
    @model = model
  end

  def method_missing(m, *args)
    raise NameError, "Decorator method '#{m}' not found" unless @model.respond_to?(m)
    @model.send(m, *args)
  end
end

example.rb

# ApplicationModel = Class.new(Sequel::Model)
# ApplicationModel < ActiveRecord::Base

class ApplicationModel
  def dec
    @decorated_dup ||= Proc.new { DecoratorClone.new(self).extend "#{self.class}Decorator".constantize }.call
  end
end

# this is user model decorator
module UserDecorator
   def full_name
     "#{first_name} #{last_name}"
   end
end

# user has db fields :first_name and :last_name
class User < ApplicationModel
end

user = User.last
user.dec.full_name # => John Smith
user.full_name # => NameError