Question

我们假设我有两个类：

#!/usr/bin/env python

class First():

        glob = 'Global data'

        def __init__(self, arg1, arg2):
                self.arg1 = arg1
                self.arg2 = arg2
                print (arg1, arg2)

class Second(First):
        def __init__(self):
                print (self.glob)

他们从脚本调用：

#!/usr/bin/env python

import classes

data1 = 'First data part'
data2 = 'Second data part'

inst1 = classes.First(data1, data2)
inst2 = classes.Second()

这很有效，好的：

$ ./script.py
('First data part', 'Second data part')
Global data

我想在arg1类中将arg2和First设为“全局”，然后在Second中使用它：

class Second(First):
        def __init__(self):
                print (self.glob, self.arg1, self.arg2)

我如何实现它？

Answer 1

class First(object):

    glob = 'Global data'

    def __init__(self, arg1, arg2):
        self.arg1 = arg1
        self.arg2 = arg2
        #print (arg1, arg2)

class Second(First):
    def __init__(self, *args):
        super(Second, self).__init__(*args)
        print (self.glob, self.arg1, self.arg2)

data1 = 'First data part'
data2 = 'Second data part'

inst1 = First(data1, data2)
inst2 = Second(data1, data2)

Answer 2

First的 init 被第二个重载，从你的第二个类调用你的父类

class Second(First):
    def __init__(self):
        super(Second, self).__init__("argument1", "argument2")
        print (self.glob, self.arg1, self.arg2)

在python3中它是这样的：

class Second(First):
    def __init__(self):
        super().__init__("argument1", "argument2")
        print (self.glob, self.arg1, self.arg2)

Answer 3

您可以在First班级__init__()方法中使用unpacking：

class First:

    def __init__(self, *args):
        for data in args:
            print(data)

# in your child class, you need to call First.__init__(), via super()

class Second(First):

    def __init__(self, *args):
        super(Second, self).__init__(*args)  # pass args to First.__init__()

用法：

import classes

i = Second("data", "data1", "data2", "data3")

使用解包允许您的类接受任意数量的参数，并使编写子类更快更容易。根据您的使用情况，有时最好使用字典解包，特别是如果您想要命名参数：

class First:

    def __init__(self, **kwargs): # note the double wildcards here
        print(kwargs.get('data1'))
        print(kwargs.get('data2'))

class Second(First):

    def __init__(self, **kwargs):
        super(Second, self).__init__(**kwargs) 

# usage

i = Second(data1="something", data2="something else", another_arg="Yahoo")

从超类继承变量

3 个答案: