delay.rb in thread-0.0.4.1

- old
+ new

@@ -11,9 +11,11 @@
 # A delay is an object that incapsulates a block which is called upon
 # value retrieval, and its result cached.
 class Thread::Delay
 	# Create a delay with the passed block.
 	def initialize (&block)
+		raise ArgumentError, 'no block given' unless block
+
 		@mutex = Mutex.new
 
 		@block = block
 	end
 