python 的 sum() 和非整数值

问题描述

有没有一种简单快捷的方法来使用非整数值的 sum()?

Is there a simple and quick way to use sum() with non-integer values?

所以我可以这样使用它:

So I can use it like this:

class Foo(object):
    def __init__(self,bar)
        self.bar=bar

mylist=[Foo(3),Foo(34),Foo(63),200]
result=sum(mylist) # result should be 300

我尝试覆盖 __add__ 和 __int__ 等，但我还没有找到解决方案

I tried overriding __add__ and __int__ etc, but I don't have found a solution yet

解决办法是实现:

 def __radd__(self, other):
    return other + self.bar

正如威尔在他的帖子中所建议的那样.但一如既往，条条大路通罗马，但我认为这是最好的解决方案，因为我的课堂不需要 __add__

as Will suggested in his post. But as always, all roads lead to Rome, but I think this is the best solution since I don't need __add__ in my class

推荐答案

这有点棘手 - sum() 函数获取开始并将其添加到下一个等等

Its a bit tricky - the sum() function takes the start and adds it to the next and so on

你需要实现 __radd__ 方法:

class T:
    def __init__(self,x):
        self.x = x
    def __radd__(self, other):
        return other + self.x

test = (T(1),T(2),T(3),200)
print sum(test)

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