Add conversion type hints

[geryogam]

Like the original poster of this Stack Overflow question, I have some functions with a parameter accepting any arguments that can be converted to int (using the int() built-in function). This is the type hint that I am currently using (based on typeshed, and I am not even sure that this list is exhaustive):

from collections.abc import Iterable
from typing import SupportsInt, SupportsIndex, Union

def f(x: Union[SupportsInt, SupportsIndex, str, bytes, bytearray]) -> Iterable:
    return range(int(x))

y = f(1)
y = f(True)
y = f('1')
y = f(b'1')
y = f(bytearray(b'1'))

It would be so much more convenient if I did not have to maintain that list.

So what do you think about adding the following type hints to the typing module?

• ConvertibleToInt, equal to Union[SupportsInt, SupportsIndex, SupportsTrunc, str, bytes, bytearray];
• ConvertibleToFloat, equal to Union[SupportsFloat, SupportsIndex, str, bytes, bytearray];
• ConvertibleToComplex, equal to Union[SupportsComplex, SupportsIndex, str, complex].

[srittau]

It makes sense to me to have these type aliases. For now, the easiest is to add them to the _typeshed module, although we plan to move some definitions from _typeshed to typing_extensions, from where they might migrate to the Python stdlib at some point.

[geryogam]

Alright. Is it planned or should I open a pull request?

[GuillaumeDesforges]

Same question, can ConvertibleToInt be imported and used?

[srittau]

ConvertibleToInt can be imported from the _typeshed module:

from typing import TYPE_CHECKING

if TYPE_CHECKING:
    from _typeshed import ConvertibleToInt

[GuillaumeDesforges]

Thanks!