问题描述
我有一个函数,它的输入参数可以是一个元素或一个元素列表.如果这个参数是单个元素,那么我将它放在一个列表中,这样我就可以以一致的方式迭代输入.
目前我有这个:
def my_func(input):如果不是 isinstance(input, list): input = [input]对于输入中的 e:...
我正在使用现有的 API,因此我无法更改输入参数.使用 isinstance() 感觉很麻烦,那么有正确的方法来做到这一点吗?
我喜欢 Andrei Vajna 对 hasattr(var,'__iter__')
的建议.请注意一些典型 Python 类型的这些结果:
这具有将字符串视为不可迭代的额外优势 - 字符串是一个灰色区域,因为有时您想将它们视为一个元素,有时则将其视为一个字符序列.
请注意,在 Python 3 中,str
类型确实具有 __iter__
属性,但这不起作用:
I have a function whose input argument can either be an element or a list of elements. If this argument is a single element then I put it in a list so I can iterate over the input in a consistent manner.
Currently I have this:
def my_func(input):
if not isinstance(input, list): input = [input]
for e in input:
...
I am working with an existing API so I can't change the input parameters. Using isinstance() feels hacky, so is there a proper way to do this?
I like Andrei Vajna's suggestion of hasattr(var,'__iter__')
. Note these results from some typical Python types:
>>> hasattr("abc","__iter__")
False
>>> hasattr((0,),"__iter__")
True
>>> hasattr({},"__iter__")
True
>>> hasattr(set(),"__iter__")
True
This has the added advantage of treating a string as a non-iterable - strings are a grey area, as sometimes you want to treat them as an element, other times as a sequence of characters.
Note that in Python 3 the str
type does have the __iter__
attribute and this does not work:
>>> hasattr("abc", "__iter__")
True
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