为什么这仅在我从 config
中的 __init__
中删除 Second
时才有效?
class First(object):
def __init__(self, config):
super().__init__(config)
print("first", config)
class Second(object):
def __init__(self, config): # <-- works only if I remove config
super().__init__(config)
print("second", config)
class Third(First, Second):
def __init__(self, config):
super().__init__(config)
print("third", config)
Third({"name": "alex"})
=> second {'name': 'alex'}
=> first {'name': 'alex'}
=> third {'name': 'alex'}
答案 0 :(得分:0)
错误消息会准确地告诉您出了什么问题:
TypeError: object.__init__() takes exactly one argument (the instance to initialize)
Second
的父类是 object
,您使用额外的参数调用它的 __init__
。
super()
只给你第一个父类,这使得它在你进行多重继承时通常没有帮助(并且经常只是简单的混淆)。如果您修复代码以消除调用 object.__init__(config)
时出现的错误,您会得到:
class First: # note that in modern Python you don't need to give object as the parent
def __init__(self, config):
print("first", config)
class Second:
def __init__(self, config):
print("second", config)
class Third(First, Second):
def __init__(self, config):
super().__init__(config)
print("third", config)
Third({"name": "alex"})
first {'name': 'alex'}
third {'name': 'alex'}
因为您的 super().__init__
调用仅调用 First
。相反,您可能希望显式调用每个父类的构造函数:
class Third(First, Second):
def __init__(self, config):
First.__init__(self, config)
Second.__init__(self, config)
print("third", config)
first {'name': 'alex'}
second {'name': 'alex'}
third {'name': 'alex'}