在操作变量值的情况下如何使用多重继承

Question

class Electronicdevice():
    Devices = 100
class Pocketgadgets(Electronicdevice):
    Pocketdevices = 40
class Phone(Pocketgadgets):
    #Phones = Devices - Pocketdevices
    pass

Samsung = Electronicdevice()
Galaxy = Pocketgadgets()
SamsungGalaxyS21 = Phone()

print(SamsungGalaxyS21.Devices)

在这种情况下，我得到预期的输出为 100，因为它继承了电子设备类的值。

但万一，我尝试执行以下操作，我收到错误“NameError: name 'Devices' is not defined”

class Electronicdevice():
    Devices = 100
class Pocketgadgets(Electronicdevice):
    Pocketdevices = 40
class Phone(Pocketgadgets):
    Phones = Devices - Pocketdevices
    pass

Samsung = Electronicdevice()
Galaxy = Pocketgadgets()
SamsungGalaxyS21 = Phone()

print(SamsungGalaxyS21.Phones)

期望得到值 60 作为输出。有人可以帮忙吗？

Answer 1

您可以尝试以下解决方案：

解决方案 1： 通过class访问variables

class Electronicdevice:
    Devices = 100


class Pocketgadgets(Electronicdevice):
    Pocketdevices = 40


class Phone(Pocketgadgets):
    Phones = Electronicdevice.Devices - Pocketgadgets.Pocketdevices


Samsung = Electronicdevice()
Galaxy = Pocketgadgets()
SamsungGalaxyS21 = Phone()

print(SamsungGalaxyS21.Phones)

60

NB: this example is independent of the inheritance, that is, even if you don't inherit from **Pocketgadgets** class, it will still work.

解决方案 2： 通过class 的instance 访问variables

class Electronicdevice:
    Devices = 100


class Pocketgadgets(Electronicdevice):
    Pocketdevices = 40


class Phone(Pocketgadgets):

    def __init__(self):
        self.Phones = self.Devices - self.Pocketdevices


Samsung = Electronicdevice()
Galaxy = Pocketgadgets()
SamsungGalaxyS21 = Phone()

print(SamsungGalaxyS21.Phones)

60