Interface Class

定义接口及抽象基类

接口(interface)和抽象类(abstract class)的作用在于，可以通过定义接口和抽象基类来实现确保子类实现了某些特定的方法

from abc import ABCMeta, abstractmethod

class fileio(metaclass=ABCMeta):
    @abstractmethod
    def read(self, maxbytes=-1):
        pass

    @abstractmethod
    def write(self, data):
        pass


f = fileio()

抽象类有个特点，就是不能实例化

Traceback (most recent call last):
  File "F:/Python/Learn Through/oop1.py", line 94, in <module>
    f = fileio()
TypeError: Can't instantiate abstract class fileio with abstract methods read, write

抽象类的目的就是让其他类继承并且实现特定的方法

from abc import ABCMeta, abstractmethod

class fileio(metaclass=ABCMeta):
    @abstractmethod
    def read(self, maxbytes=-1):
        pass

    @abstractmethod
    def write(self, data):
        pass


class text(fileio):
    def read(self, maxbytes=-1):
        print('read')
    def write(self, data):
        print(data)

t = text()
t.write('123')

输出

123

如果继承抽象类的子类没有实现对应的方法，在运行时则会报错

from abc import ABCMeta, abstractmethod
class fileio(metaclass=ABCMeta):
    @abstractmethod
    def read(self, maxbytes=-1):
        pass

    @abstractmethod
    def write(self, data):
        pass

class text(fileio):
    def read(self, maxbytes=-1):
        print('read')
    def writa(self, data):
        print(data)
    def update(self):
        print('update')

t = text()
t.write(123)

输出

Traceback (most recent call last):
  File "F:/Python/Learn Through/oop1.py", line 100, in <module>
    t = text()
TypeError: Can't instantiate abstract class text with abstract methods write