面向接口编程

In [1]: import abc

In [2]: class Bird(abc.ABC):
   ...:     @abc.abstractmethod
   ...:     def fly(self):
   ...:         pass
   ...:

In [3]: class Parrot(Bird):
   ...:     pass
   ...:

In [4]: Parrot().fly()
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-4-beb5d307db79> in <module>
----> 1 Parrot().fly()

TypeError: Can't instantiate abstract class Parrot with abstract methods fly

In [5]: class Parrot(Bird):
   ...:     def fly(self):
   ...:         print("flying")
   ...:

In [6]: Parrot().fly()
flying

可以看到，如果我们继承了 Bird 却没有实现接口的话，直接调用就会报错。