今天是Behavioral patterns, 行为型模式, 第一部分==b: 1) Chain of Responsibility Indent: Avoid coupling the sender

Said ruby 1.9 will add a new useful feature named external iterator - the kind of iterator you used in Java/Cpp. It's interesting to implement one ourself by using callcc, in 1.8.6. Note: It's easy to turn this piece of code into a module or make the