面向對象【七】接口繼承

python之接口繼承

 

接口繼承

接口繼承就是（基類）父類定義好2個函數屬性（接口），全部的子類必須有這2個函數屬性，缺一不可，不是說省代碼的，是用來作強制性約束的

基類裏面的方法不用具體的實現，只是一個規範而已

1.1實現一個一切皆文件的概念

class Disk:
    def read(self):
        pass
    def write(self):
        pass
class Cdrom:
    def read(self):
        pass
    def write(self):
        pass
class Mem:
    def read(self):
        pass
    def write(self):
        pass

1.2能夠定義一個基類，對上面代碼進行改進

class Allfile:
    def read(self):
        pass
    def write(self):
        pass
class Disk(Allfile):
    def read(self):
        print("disk read")
    def write(self):
        print("disk write")
class Cdrom(Allfile):
    def read(self):
        print("cdrom read")
    def write(self):
        print("cdrom write")
class Mem(Allfile):
    def read(self):
        print("mem read")
    def write(self):
        print("mem write")

1.3可是子類也能夠不按照你規定的出牌，Mem就是不聽話，他不定義write的函數屬性，而後就會從父類找。父類裏面又是pass

class Allfile:
    def read(self):
        pass
    def write(self):
        pass
class Disk(Allfile):
    def read(self):
        print("disk read")
    def write(self):
        print("disk write")
class Cdrom(Allfile):
    def read(self):
        print("cdrom read")
    def write(self):
        print("cdrom write")
class Mem(Allfile):
    def read(self):
        print("mem read")
m1=Mem()
m1.read()
m1.write()

C:\python35\python3.exe D:/pyproject/day25/接口繼承.py

mem read

1.4因此python就有一個專門的模塊來實現這個強制性的約束子類，模塊叫abc

導入模塊abc，給父類2個屬性加上裝飾器以後，若是子類再少屬性的話，就直接報錯了，這樣就強制性的約束了子類必須有父類的2個方法了

import abc
class Allfile(metaclass=abc.ABCMeta):
    @abc.abstractstaticmethod
    def read(self):
        pass
    @abc.abstractstaticmethod
    def write(self):
        pass
class Disk(Allfile):
    def read(self):
        print("disk read")
    def write(self):
        print("disk write")
class Cdrom(Allfile):
    def read(self):
        print("cdrom read")
    def write(self):
        print("cdrom write")
class Mem(Allfile):
    def read(self):
        print("mem read")
m1=Mem()

TypeError: Can't instantiate abstract class Mem with abstract methods write

1.5當子類Mem也加上write這個方法以後就能夠正常運行了

import abc
class Allfile(metaclass=abc.ABCMeta):
    @abc.abstractstaticmethod
    def read(self):
        pass
    @abc.abstractstaticmethod
    def write(self):
        pass
class Disk(Allfile):
    def read(self):
        print("disk read")
    def write(self):
        print("disk write")
class Cdrom(Allfile):
    def read(self):
        print("cdrom read")
    def write(self):
        print("cdrom write")
class Mem(Allfile):
    def read(self):
        print("mem read")
    def write(self):
        print("mem write")
m1=Mem()
m1.read()
m1.write()

mem read

mem write