Python 类中“cls"和“self"之间的区别? [英] Difference between 'cls' and 'self' in Python classes?

问题描述

为什么在 Python 类中有时使用 cls 而不是 self 作为参数?

Why is cls sometimes used instead of self as an argument in Python classes?

例如:

class Person:
    def __init__(self, firstname, lastname):
        self.firstname = firstname
        self.lastname = lastname

    @classmethod
    def from_fullname(cls, fullname):
        cls.firstname, cls.lastname = fullname.split(' ', 1)

推荐答案

"self" 和 "cls" 的区别定义在 PEP 8 .正如 Adrien 所说，这不是强制性的.这是一种编码风格.PEP 8 说:

The distinction between "self" and "cls" is defined in PEP 8 . As Adrien said, this is not mandatory. It's a coding style. PEP 8 says:

函数和方法参数:

总是使用 self 作为实例方法的第一个参数.

Always use self for the first argument to instance methods.

始终使用 cls 作为类方法的第一个参数.

Always use cls for the first argument to class methods.

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