抽象基类

Python 面向对象编程进阶

Jake Roach

Data Engineer

抽象基类

抽象基类通过定义所有子类都必须实现的抽象方法来创建类的蓝图

确保一组类具有一致行为
@abstractmethod 装饰器
设计为被继承，而非直接实例化
抽象基类中不必所有方法都是抽象的（也可有具体方法）

class School:
    # Do things such as enroll 
    # and add a course

class MiddleSchool:
    # Play an instrument, join a club
    # but must enroll and add courses

class HighSchool:
    # Play a varsity sport, apply
    # for college, but must enroll 
    # and add courses

创建抽象基类

from abc import ABC, abstractmethod


# Create an abstract base class that inherits
# from ABC
class School(ABC):
    @abstractmethod
    def enroll(self):
        # This method must be implemented
        # in classes that inherit from it
        pass


    # Concrete methods are inherited
    def graduate(self):
        print("Congrats on graduating!")

继承 abc 模块中的 ABC 类
pass
任何继承 School 的类都必须实现 enroll() 方法
也可实现具体方法

实现抽象基类

class HighSchool(School):
    def enroll(self):
        print("Welcome to high school!")

# Create an instance of HighSchool
high_school = HighSchool()
high_school.enroll()

Welcome to high school!

high_school.graduate()

Congrats on graduating!

HighSchool 必须定义 enroll() 方法
若未定义 enroll() 会抛出 TypeError
HighSchool 继承 graduate() 方法

多个抽象方法

class School(ABC):
    @abstractmethod
    def enroll(self):
        pass

    @abstractmethod
    def add_course(self, course_name):
        pass

    def graduate(self):
        print("Congrats on graduating!")

两个抽象方法：enroll() 和 add_course()

class HighSchool(School):
    def __init__(self):
        self.courses = []

    # Implementing abstract method
    def enroll(self):
        print("Welcome to high school!")

    # Implementing abstract method
    def add_course(self, course_name):
        self.courses.append(course_name)
        print(f"You enrolled in {course_name}")

Passons à la pratique !

Python 面向对象编程进阶