Python：重载特定类型的运算符

发布于 2024-09-08 06:07:33 字数 557 浏览 1 评论 0原文

我希望能够让我的类的运算符以我定义的方式与常规类型进行交互。比方说，我有：

class Mynum(object):
  def __init__(self, x):
   self.x = x
  def __add__(self, other):
   return self.x + other.x

a = Mynum(1)
b = Mynum(2)

print a+b

这工作得很好，但现在如果我尝试这样做：

print a+2

我收到一个错误，因为 int 没有名为 x 的成员。如何在类中定义 Mynum + int ？这听起来像是装饰器或元类的工作，但我对它们的用法非常不熟悉。这个问题看起来很相似，但不完全相同。

原文

I'd like to be able to have the operator of my class interact with regular types in a way that I define. Lets say, for example, I have:

class Mynum(object):
  def __init__(self, x):
   self.x = x
  def __add__(self, other):
   return self.x + other.x

a = Mynum(1)
b = Mynum(2)

print a+b

This works just fine, but now if I try to do:

print a+2

I get an error since an int does not have a member named x. How do I define Mynum + int in the class? This sounds like a job for decorators or metaclasses, but I'm terribly unfamiliar with their usage. This question seems similar, but not quite identical.

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七婞 2024-09-15 06:07:33

def __add__(self, other):
    if isinstance(other, self.__class__):
        return self.x + other.x
    elif isinstance(other, int):
        return self.x + other
    else:
        raise TypeError("unsupported operand type(s) for +: '{}' and '{}'").format(self.__class__, type(other))

def __add__(self, other):
    if isinstance(other, self.__class__):
        return self.x + other.x
    elif isinstance(other, int):
        return self.x + other
    else:
        raise TypeError("unsupported operand type(s) for +: '{}' and '{}'").format(self.__class__, type(other))

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梦过后 2024-09-15 06:07:33

class Mynum(object):
    def __init__(self, x):
        self.x = x
    def __add__(self, other):
        try:
            return self.x + other.x
        except AttributeError:
            return self.x + other
    __radd__=__add__

a = Mynum(1)
b = Mynum(2)

print(a+b)
# 3
print(a+2)
# 3
print(2+a)
# 3

class Mynum(object):
    def __init__(self, x):
        self.x = x
    def __add__(self, other):
        try:
            return self.x + other.x
        except AttributeError:
            return self.x + other
    __radd__=__add__

a = Mynum(1)
b = Mynum(2)

print(a+b)
# 3
print(a+2)
# 3
print(2+a)
# 3

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静若繁花 2024-09-15 06:07:33

为什么要使用额外的切换和/或异常处理？使用以下方法将是一种更简单的方法：

class MyNum(object):
    def __init__(self, x):
        self.x = x
    def __add__(self, other):
        return other + self.x
    __radd__ = __add__
x = MyNum(5)
y = MyNum(6)
print x + 2
7
print 2 + x
7
print x + y
11
print y + x
11

Why use the extra switching and/or exception handling? Using the following would be a simpler approach:

class MyNum(object):
    def __init__(self, x):
        self.x = x
    def __add__(self, other):
        return other + self.x
    __radd__ = __add__
x = MyNum(5)
y = MyNum(6)
print x + 2
7
print 2 + x
7
print x + y
11
print y + x
11

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~没有更多了~