抽象基底類別

Python 物件導向程式設計進階

Jake Roach

Data Engineer

抽象基底類別

抽象基底類別透過定義「必須由所有子類別實作」的「抽象方法」，為類別建立藍圖。

確保一組類別有共同行為
@abstractmethod 修飾器
用來被繼承，不用來實例化
不必所有方法都抽象（可有具體方法）

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

建立抽象基底類別

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!")

從 abc 模組的 ABC 類別繼承
pass
任何繼承 School 的類別都必須實作 enroll() 方法
也可定義具體方法

實作抽象基底類別

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 必須定義 enroll() 方法
若未定義 enroll() 會拋出 TypeError
HighSchool 會繼承 graduate() 方法

多個抽象方法

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

    @abstractmethod
    def add_course(self, course_name):
        pass

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

兩個抽象方法：enroll() 與 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}")

一起來練習吧！

Python 物件導向程式設計進階