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"