Python类中的"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 代替 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" 之间的区别在 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 a mandatory. It's a coding style. PEP 8 says:

函数和方法参数:

始终将 self 用作实例方法的第一个参数.

Always use self for the first argument to instance methods.

对于类方法的第一个参数，始终使用 cls .

Always use cls for the first argument to class methods.

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