如何在 Python 中实现虚拟方法? [英] How to implement virtual methods in Python?

问题描述

我知道 PHP 或 Java 中的虚方法.

I know virtual methods from PHP or Java.

如何在 Python 中实现它们?

How can they be implemented in Python?

或者我必须在抽象类中定义一个空方法并覆盖它吗?

Or have I to define an empty method in an abstract class and override it?

推荐答案

当然，您甚至不必在基类中定义方法.在 Python 中方法比虚拟更好 - 它们是完全动态的，因为 Python 中的输入是鸭子输入.

Sure, and you don't even have to define a method in the base class. In Python methods are better than virtual - they're completely dynamic, as the typing in Python is duck typing.

class Dog:
  def say(self):
    print "hau"

class Cat:
  def say(self):
    print "meow"

pet = Dog()
pet.say() # prints "hau"
another_pet = Cat()
another_pet.say() # prints "meow"

my_pets = [pet, another_pet]
for a_pet in my_pets:
  a_pet.say()

Python 中的

Cat 和 Dog 甚至不必从公共基类派生来允许这种行为 - 您可以免费获得它.也就是说，一些程序员更喜欢以更严格的方式定义他们的类层次结构，以更好地记录它并强加一些类型的严格性.这也是可能的 - 例如参见 abc 标准模块.

Cat and Dog in Python don't even have to derive from a common base class to allow this behavior - you gain it for free. That said, some programmers prefer to define their class hierarchies in a more rigid way to document it better and impose some strictness of typing. This is also possible - see for example the abc standard module.

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