Python是类在同一个类的定义中的实例

class my_class: def __add__(self, other: "my_class") -> "my_class": if isinstance(other, some_other_class): return other + self elif isinstance(other, my_class): return <special_adding_technique> else: raise NotImplementedError()

你可以参考 my_class 它的内部很好。你不能提及 我的班 当它被定义时(在任何方法之外,在类定义范围的顶层,或在函数的参数定义中),但是你可以在一个方法中引用它,直到你完成定义后才会被调用 我的班 .这里唯一的问题是基于字符串的注释有点难看,可以绕过自引用限制,这可以通过 __future__ 进口

from __future__ import annotations  # Supported as of 3.7, on by default beginning in 3.11

class my_class:
    def __add__(self, other: my_class) -> my_class:
        if isinstance(other, some_other_class):
            return other + self
        elif isinstance(other, my_class):
            return <special_adding_technique>
        return NotImplemented   # When you can't work with the other type, you're supposed
                                # to return the NotImplemented singleton, not raise
                                # NotImplementedError, where the latter is for completely
                                # unimplemented functionality, usually in an ABC

顺便说一句,Python类是 lowercase 或 lowercase_with_underscores ; 类使用 CapWords ,所以这个类应该命名为 MyClass 遵守PEP8。