如何用Python的@dataclass实现含match/case的算术运算类？

完整代码实现 #

from dataclasses import dataclass
from numbers import Number

@dataclass
class MyClass:
    x: float
    y: float

    def __add__(self, other):
        match other:
            case Number():
                return MyClass(float(other) + self.x, self.y)
            case MyClass(ot_x, ot_y):
                return MyClass(self.x + ot_x, self.y + ot_y)
            case _:
                return NotImplemented

    __radd__ = __add__

    def __sub__(self, other):
        match other:
            case Number():
                return MyClass(self.x - float(other), self.y)
            case MyClass(ot_x, ot_y):
                return MyClass(self.x - ot_x, self.y - ot_y)
            case _:
                return NotImplemented

    def __rsub__(self, other):
        match other:
            case Number():
                return MyClass(float(other) - self.x, -self.y)
            case _:
                return NotImplemented

    def __mul__(self, other):
        match other:
            case Number():
                num = float(other)
                return MyClass(self.x * num, self.y * num)
            case MyClass(ot_x, ot_y):
                return MyClass(self.x * ot_x, self.y * ot_y)
            case _:
                return NotImplemented

    __rmul__ = __mul__

    def __truediv__(self, other):
        match other:
            case Number():
                num = float(other)
                if num == 0:
                    raise ZeroDivisionError("Cannot divide by zero")
                return MyClass(self.x / num, self.y / num)
            case MyClass(ot_x, ot_y):
                if ot_x == 0 or ot_y == 0:
                    raise ZeroDivisionError("Cannot divide by zero")
                return MyClass(self.x / ot_x, self.y / ot_y)
            case _:
                return NotImplemented

    def __rtruediv__(self, other):
        match other:
            case Number():
                num = float(other)
                if self.x == 0 or self.y == 0:
                    raise ZeroDivisionError("Cannot divide by zero")
                return MyClass(num / self.x, num / self.y)
            case _:
                return NotImplemented

    def __neg__(self):
        return MyClass(-self.x, -self.y)

    def __mod__(self, other):
        match other:
            case Number():
                num = float(other)
                return MyClass(self.x % num, self.y % num)
            case MyClass(ot_x, ot_y):
                return MyClass(self.x % ot_x, self.y % ot_y)
            case _:
                return NotImplemented

    def __pow__(self, other):
        match other:
            case Number():
                num = float(other)
                return MyClass(self.x ** num, self.y ** num)
            case MyClass(ot_x, ot_y):
                return MyClass(self.x ** ot_x, self.y ** ot_y)
            case _:
                return NotImplemented

关键方法说明 #

• 减法（sub/rsub）：
  • __sub__ 处理self - other逻辑，对Number仅操作x分量，对MyClass做分量相减
  • __rsub__ 处理other - self逻辑，当other是Number时，用数值减去self.x，y分量取反（对应0 - self.y）
• 乘法（mul）：
  • 支持标量乘法（Number）和分量乘法（MyClass），复用__mul__作为__rmul__，因为标量乘法满足交换律
• 除法（truediv/rtruediv）：
  • 两类除法都添加了除零判断，__rtruediv__处理数值除以MyClass的场景，分别用数值除以x、y分量
• 取反（neg）：
  • 单目运算，直接返回x、y取反的新实例
• 取模（mod）：
  • 支持Number和MyClass的分量取模运算
• 幂运算（pow）：
  • 支持Number和MyClass的分量幂运算
• 类型兼容处理：
  • 所有方法都添加了默认分支返回NotImplemented，让Python自动尝试反向运算或抛出类型错误，符合Python运算符重载规范

内容的提问来源于stack exchange，提问作者Heike Heinrich