在Python中，如何确定一个对象是否可迭代？

Question

有像isiterable这样的方法吗？到目前为止我找到的唯一解决办法就是打电话

hasattr(myObj, '__iter__')

但我不知道这是多么愚蠢的证据。

Answer 1

鸭子打字

try:
    iterator = iter(theElement)
except TypeError:
    # not iterable
else:
    # iterable

# for obj in iterator:
#     pass

类型检查

使用Abstract Base Classes。它们至少需要Python2.6，并且只适用于新样式的类。

from collections.abc import Iterable   # import directly from collections for Python < 3.3

if isinstance(theElement, Iterable):
    # iterable
else:
    # not iterable

但是，iter()更可靠，如by the documentation所述：

Checking isinstance(obj, Iterable) detects classes that are registered as Iterable or that have an __iter__() method, but it does not detect classes that iterate with the __getitem__() method. The only reliable way to determine whether an object is iterable is to call iter(obj).