导入next()python 2.5 [英] import next() python 2.5

问题描述

我正在使用itertools中成对配方的略微更改版本，如下所示

I'm using a slightly altered version of the pairwise recipe from itertools which looks like this

def pairwise(iterable):
    "s -> (s0,s1), (s1,s2), (s2, s3), ..."
    a, b = tee(iterable)
    next(b, None)
    return zip(a, b) 

现在事实证明，我需要使用 python 2.5 运行代码，其中next()函数将引发以下异常:

Now it turns out I need to run the code with python 2.5 where the next() function throws the following exception:

<type 'exceptions.NameError'>: global name 'next' is not defined

是否可以在python 2.5中使用next()?还是我需要修改该功能以使其正常工作?

Is there a way to use next() with python 2.5? Or how do I need to modify the function to make it work anyhow?

推荐答案

您可以轻松地自己提供此函数的定义:

You can easily provide a definition of this function yourself:

_sentinel = object()
def next(it, default=_sentinel):
    try:
        return it.next()
    except StopIteration:
        if default is _sentinel:
            raise
        return default

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