DSL for constructing object graph

dsl_object.rb

class DslObject
  def initialize(*args, &block)
    args.zip(self.class.properties).each do |arg, property|
      instance_variable_set("@#{property}", arg)
    end
    instance_eval(&block) if block
  end

  def self.properties(*properties)
    if properties.empty?
      @properties
    else
      @properties = properties
      properties.each do |property|
        class_eval %{def #{property}(*args, &block)
          @#{property} = args.first unless args.empty?
          block ? instance_eval(&block) : @#{property}
        end}
      end
    end
  end

  def self.has_one(property)
    class_eval %{def #{property}(*args, &block)
      if !args.empty? || block
        @#{property} ||= #{property.to_s.camelize}.new(*args, &block)
      end
      @#{property}
    end}
  end

  def self.has_many(collection)
    class_eval %{attr_reader :#{collection}

    def #{collection.to_s.singularize}(*args, &block)
      puts "#{collection.to_s.singularize} \#{args.inspect}"
      obj = #{collection.to_s.singularize.to_s.classify}.new(*args, &block)
      (@#{collection} ||= []) << obj
    end}
  end
end

Also, Textmate seems to highlight this properly FWIW. As well as Github, obviously :)

I got correct results by replacing has_many's %{} with %[], fwiw.

http://cl.ly/3L2y1G1e2a0m0D3c0Y2Q