[英]multiple inheritance, TypeError: __init__() takes 2 positional arguments but 3 were given
[英]inheritance TypeError: __init__() takes from 1 to 2 positional arguments but 8 were given
我正在尝试遵循与 Python OOP 书籍中的继承相关的示例。 但是,我面临一个错误。
from __future__ import annotations
class ContactList(list["Contact"]):
def search(self, name: str) -> list["Contact"]:
matching_contacts: list["Contact"] = []
for contact in self:
if name in contact.name:
matching_contacts.append(contact)
return matching_contacts
class Contact:
all_contacts = ContactList()
def __init__(self, /, name: str = "", email: str = "", **kwargs) -> None:
super().__init__(**kwargs)
self.name = name
self.email = email
self.all_contacts.append(self)
def __repr__(self) -> str:
return f"{self.__class__.__name__}(" f"{self.name!r}, {self.email!r}" f")"
class AddressHolder:
def __init__(self, /, street: str = "", city: str = "", state: str = "", code: str = "", **kwargs) -> None:
super().__init__(**kwargs)
self.street = street
self.city = city
self.state = state
self.code = code
class Friend(Contact, AddressHolder):
def __init__(self, /, phone: str = "", **kwargs) -> None:
super().__init__(**kwargs)
self.phone = phone
f1 = Friend("Dusty", "dusty@example.com", "Elm Street", "New York City", "New York", "1100", "123-456-7890")
print(f1)
错误是:
Traceback (most recent call last):
File "test.py", line 41, in <module>
f1 = Friend("Dusty", "dusty@example.com", "Elm Street", "New York City", "New York", "1100", "123-456-7890")
TypeError: Friend.__init__() takes from 1 to 2 positional arguments but 8 were given
由于Friend
正在调用super().__init__(**kwargs)
并继承自AddressHolder
和Contact
,因此您希望这些类的初始化程序所需的所有参数都通过kwargs
提供(即,作为关键字参数)。 您可以通过在Friend.__init__
中打印kwargs
并使用关键字传递参数来了解其工作原理:
class Friend(Contact, AddressHolder):
def __init__(self, /, phone: str = "", **kwargs) -> None:
# Added line.
print(kwargs)
super().__init__(**kwargs)
self.phone = phone
# Passing phone as positional argument, all the rest as keyword arguments.
f1 = Friend("123-456-7890", name="Dusty", email="dusty@example.com", street="Elm Street", city="New York City", state="New York", code="1100")
print(f1)
{'name': 'Dusty', 'email': 'dusty@example.com', 'street': 'Elm Street', 'city': 'New York City', 'state': 'New York', 'code': '1100'}
Friend('Dusty', 'dusty@example.com')
kwargs
将收集您提供的所有未在Friend.__init__()
的签名中指定的关键字参数。 由于您没有关键字参数,因此所有关键字参数都以kwargs
结尾。 super().__init__(**kwargs)
将调用Contact.__init__(**kwargs)
和AddressHolder.__init__(**kwargs)
,提供创建实例所需的所有参数。
您将所有参数作为positional传递,即没有关键字。 您的错误是告诉您这与Friend.__init__()
的签名不对应,它只允许两个位置参数( self
和phone
)。 当您输入关键字时,错误就会消失,因为所有这些参数都以kwargs
结尾。
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