Is there a Python typing class that means "set, list, or tuple"-like thing?

user_4185992 0
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Is there a Python typing class for a collection of items that is not a mapping -- i.e., a set, list, or tuple, but not a dict? I.e., does this Unicorn exist?

>>> from typing import Unicorn
>>> isinstance({1, 2, 3}, Unicorn)
True
>>> isinstance([1, 2, 3], Unicorn) 
True
>>> isinstance((1, 2, 3), Unicorn)
True
>>> isinstance({1: 'a', 2: 'b'}, Unicorn)
False

Collection sure looked promising but dicts are Collections too.

type-hinting collections python
2 Answers

Why not simply use:

from typing import List, Tuple, Set, Union


def test(x):
    print(isinstance(x, (List, Tuple, Set)))


def typed_f(x: Union[List, Tuple, Set]):
    print(x)


test({1, 2, 3})
test([1, 2, 3])
test((1, 2, 3))
test({1: 'a', 2: 'b'})

Result:

True
True
True
False

And the typing of typed_f is typical usage, so this would get you a warning in a good IDE:

typed_f({1: 'a', 2: 'b'})
user_43901600

No, not that I know of.

This helper function I wrote a while ago may help you though, depending on what your goal is;

def is_iterable(item):
    return hasattr(item, "__iter__") and not isinstance(item, dict)

You can easily add further exceptions in the isinstance call if required.

user_15942860
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