Does anyone know why block_given? always returns false?

yield.rb

class Configuration
	def create_method(name, &block)
		self.class.send(:define_method, name, &block )	
	end
		
	def add_configuration(name)
  		create_method "#{name.to_s}=" do |val|
  			instance_variable_set("@#{name}",val)		
		end

  		create_method name do
  			puts "method:#{name}"
  			puts "hasblock:#{block_given?}"
    		yield(instance_variable_get("@#{name}")) if block_given?
    		instance_variable_get("@#{name}")
  		end
	end

	def test=val
		@val = val
	end

	def test
		yield(@test) if block_given?
    	@test
	end

end

conf = Configuration.new
conf.test = {:a => 1, :b => 2}
conf.test do |p|
	puts "yield test"
end
conf.add_configuration :foo
conf.foo = {:a => 1, :b => 2}
conf.foo do |f|
	puts "yield foo"
end

I'm having the same issue with ruby 1.8.7