Python 简明教程
Python - Abstraction
Abstraction 是 object-oriented programming 中的一个重要原则。它指一种编程方法，通过该方法仅公开对象的相关数据，而隐藏所有其他详细信息。这一方法有助于降低复杂性并提高应用程序开发的效率。
Abstraction is one of the important principles of object-oriented programming. It refers to a programming approach by which only the relevant data about an object is exposed, hiding all the other details. This approach helps in reducing the complexity and increasing the efficiency of application development.
Types of Python Abstraction
有两种类型的抽象。一种是 data abstraction ，其中原始数据通过数据结构隐藏起来，数据结构可以在内部通过隐藏数据实体工作。另一种类型称为 process abstraction 。它指隐藏进程的底层实现细节。
There are two types of abstraction. One is data abstraction, wherein the original data entity is hidden via a data structure that can internally work through the hidden data entities. Another type is called process abstraction. It refers to hiding the underlying implementation details of a process.
Python Abstract Class
在面向对象编程术语中，如果一个类无法被实例化，即你不能拥有一个抽象类的对象，那么这个类被称为抽象类。但是，你可以把它作为一个基础类或父类来构建其他类。
In object-oriented programming terminology, a class is said to be an abstract class if it cannot be instantiated, that is you can have an object of an abstract class. You can however use it as a base or parent class for constructing other classes.
Create an Abstract Class
若要在 Python 中创建一个抽象类，它必须继承在 ABC 模块中定义的 ABC 类。此模块可在 Python 的标准库中找到。此外，该类必须至少具有一种抽象方法。同样，抽象方法是一种无法调用但可以重写的方法。您需要使用 @abstractmethod 装饰器来装饰它。
To create an abstract class in Python, it must inherit the ABC class that is defined in the ABC module. This module is available in Python’s standard library. Moreover, the class must have at least one abstract method. Again, an abstract method is the one which cannot be called but can be overridden. You need to decorate it with @abstractmethod decorator.
Example: Create an Absctract Class
from abc import ABC, abstractmethod
class demo(ABC):
@abstractmethod
def method1(self):
print ("abstract method")
return
def method2(self):
print ("concrete method")demo 类继承自 ABC 类。有一个 method1()，它是一个抽象方法。注意，该类可具有其他非抽象（具体）方法。
The demo class inherits ABC class. There is a method1() which is an abstract method. Note that the class may have other non-abstract (concrete) methods.
如果你尝试声明一个 demo 类的对象，Python 会引发 TypeError：
If you try to declare an object of demo class, Python raises TypeError −
obj = demo()
^^^^^^
TypeError: Can't instantiate abstract class demo with abstract method method1demo 类可以在此处用作另一个类的父类。但子类必须覆盖父类中的抽象方法。否则，Python 会抛出此错误 −
The demo class here may be used as parent for another class. However, the child class must override the abstract method in parent class. If not, Python throws this error −
TypeError: Can't instantiate abstract class concreteclass with abstract method method1Abstract Method Overriding
因此，具有抽象 method overridden 的子类在以下 example 中给出：
Hence, the child class with the abstract method overridden is given in the following example −
Example
from abc import ABC, abstractmethod
class democlass(ABC):
@abstractmethod
def method1(self):
print ("abstract method")
return
def method2(self):
print ("concrete method")
class concreteclass(democlass):
def method1(self):
super().method1()
return
obj = concreteclass()
obj.method1()
obj.method2()