增加int对象 [英] increment int object

问题描述

在python中有没有办法增加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'++ 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，没有办法，看起来我将不得不写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mutable int，你必须使用所有int方法构建自己的类

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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