递增 int 对象

问题描述

python 中有没有办法在适当的位置增加 int 对象，int 似乎没有实现 __iadd__ 所以 += 1 实际上返回一个新对象

Is there a way in python to increment int object in place, int doesn't seem to implement __iadd__ so += 1 actually returns a new object

>>> n=1
>>> id(n)
9788024
>>> n+=1
>>> id(n)
9788012

我想要的是 n 保持指向同一个对象.

What I want is n to remain pointing to same object.

目的:我有从 int 派生的类，我想为该类实现 C 类型的 '++n' 运算符

Purpose: I have class derived from int and I want to implement C type '++n' operator for that class

结论:好的，因为 int 是不可变的，所以没有办法，看起来我将不得不编写我自己的类这样的东西

Conclusion: ok as int is immutable there is no way, looks like i will have to write my own class something like this

class Int(object):
    def __init__(self, value):
        self._decr = False
        self.value = value

    def __neg__(self):
        if self._decr:
            self.value -= 1
        self._decr = not self._decr
        return self

    def __str__(self):
        return str(self.value)

    def __cmp__(self, n):
        return cmp(self.value, n)

    def __nonzero__(self):
        return self.value

n = Int(10)
while --n:
    print n

推荐答案

int 是不可变的，所以如果你想要一个可变的 int"，你必须用所有 int 的方法构建你自己的类

ints are immutable, so you'll have to build your own class with all the int's methods if you want a "mutable int"

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