CODEWITHSUNDEEP
python-2.7pycharmtype-hinting
pseudoDust
pseudoDust

Reputation: 1386

Python 2.7 type hinting callable types in PyCharm

I'm trying to use type hinting in python 2.7 as described here.

I have a function that expects a callable (a function) with a specific signature as a parameter and I can't figure out how to annotate it.

I've tried

def set_function(self, function):
    # type: ((int) -> None) -> None

But PyCharm shows an expected ')' and unexpected tokens errors

I can't seem to find any documentation for this...

Upvotes: 5

Views: 3291

Answers (1)

Michael0x2a
Michael0x2a

Reputation: 64288

The correct way to document a callable within Pycharm (or within any other tool that understands PEP 484 type hints) is like so:

from typing import Callable

def set_function(self, function):
    # type: (Callable[[int], None]) -> None
    ...

Since you're using Python 2, you'll need to install the typing module from PyPi, if you haven't already. (typing was added to Python's standard library in 3.5, the module on PyPi is a backport).

You can find more information on using the typing module in Python's documentation, and within the documentation for mypy.

(If you're not aware, mypy is a command line tool that also understands PEP 484 type hints and will also statically analyze and typecheck your code. It is an independent effort from Pycharm's built-in type checker. Since both Pycharm and mypy use PEP 484 types, mypy's documentation is often a good place to start looking to learn more about using type hints.)

Upvotes: 7

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