《Head First Design Pattern》--开篇： 鸭子的故事
有各种各样的鸭子（酱鸭、板鸭、黑头鸭、野鸭、盐水鸭...），特征是Quack（嘎嘎叫），Swim（游水）。
于是定义的一个SuperDuck（父类），里面有方法Quack、Swim、Display显示！
子类比如黑头鸭、RedHeadDuck，重写Display方法！
But Now We need the ducks to Fly!
How to do?
（鸭子要可以飞，怎么办？）
I Just need to add a fly() method in the SuperDuck(父类),then all the ducks will inherit it.
Now's my time to really show my true OO genius!(我真是个OO的天才啊，哈哈！)
They just give a demo and there were rubber duckies flying around the screen!
Was this idea of a joke?
(他们只不过做了一个让好多橡皮的鸭子满屏幕飞的演示！
(他们只不过做了一个让好多橡皮的鸭子满屏幕飞的演示！
这是在开玩笑吗？）
不是所有的鸭子都能飞的呀！！！
Thinks about inheritance(考虑一下继承)
我可以在RubberDuck（橡皮鸭）中重写Fly的方法。
But then what happens when wu add wooden decoy ducks（木头鸭），它既不能Quack叫，也不能Fly。
在木头鸭重写Quack（）、Fly（）？？？？
How about a interface？
I could take the fly() out of the SuperDuck(父类)，and make a flyable() interface with a fly() method. That way,only the ducks that are supposed to fly will implement that interface and have a fly() method....and I might as well make a Quackable(嘎嘎),too，since not all the ducks can quack!
(接口怎么样？
我可以把Fly从父类中剥离出来，变成一个接口，如果有鸭子可以飞，那么这只鸭子就实现这个接口。 Quack(嘎嘎叫)也是类似的.）
That is , like , the dumbest idea you've come up with.Can you say "duplicate code"?If you thought having to override a few methods was bad,How are you gonna feel when you need to make a little change to the flying behavior... in all 48 of the flying Duck subclass?!
（现在你可以说copy代码。那么我们如果对flying 有一个小小的改变怎么样？所有48个用到这个接口的子类都要改变一下，Copy48份？？？？？）
How we can do next？？？
到底该怎么办？
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