In Python, how do I determine if an object is iterable?
iterable, python
Solution
Checking for `__iter__` works on sequence types, but it would fail on e.g. strings in Python 2. I would like to know the right answer too, until then, here is one possibility (which would work on strings, too):
try:
some_object_iterator = iter(some_object)
except TypeError as te:
print(some_object, 'is not iterable')
The `iter` built-in checks for the `__iter__` method or in the case of strings the `__getitem__` method.
Another general pythonic approach is to assume an iterable, then fail gracefully if it does not work on the given object. The Python glossary:
Pythonic programming style that determines an object's type by inspection of its method or attribute signature rather than by explicit relationship to some type object ("If it looks like a duck and quacks like a duck, it must be a duck.") By emphasizing interfaces rather than specific types, well-designed code improves its flexibility by allowing polymorphic substitution. Duck-typing avoids tests using type() or isinstance(). Instead, it typically employs the EAFP (Easier to Ask Forgiveness than Permission) style of programming.
...
try:
_ = (e for e in my_object)
except TypeError:
print(my_object, 'is not iterable')
The `collections` module provides some abstract base classes, which allow to ask classes or instances if they provide particular functionality, for example:
from collections.abc import Iterable
if isinstance(e, Iterable):
# e is iterable
However, this does not check for classes that are iterable through `__getitem__`.
Problem
Is there a method like `isiterable`? The only solution I have found so far is to call ``` hasattr(myObj, '__iter__') ``` But I am not sure how fool-proof this is.