CODEWITHSUNDEEP
pythonfunctiontypesany
Kazafka
Kazafka

Reputation: 17

Using 'any' when defining a function

I know that the title might not tell exactly what am I asking for, so here's a little block of code that should explain a little bit more:

def echo(msg: any) -> None:
    print(str(msg))

Since 'any' is a function, I am asking if syntax like that is correct. I know that I should give a type like 'object' or etc. but I just want to know if the syntax is ok or not.

Upvotes: 0

Views: 460

Answers (3)

Weibeu
Weibeu

Reputation: 86

The syntax is really fine. Type annotations just expects you to specify whatever type or object your variable is of. So here in your case its a valid syntax and everything will work fine as any is object too. Its just a builtin function. If you pass your code through interpreter and inspect the annotations everything will be as expected.

>>> import typing
>>>
>>> def echo(msg: any) -> None:
...     print(str(msg))
...
>>>
>>> echo.__annotations__
{'msg': <built-in function any>, 'return': None}
>>>

As you would expect, here msg is assumed to be of type <built-in function any>.

However if you pass same using Python type checks like mypy then it would give you an error. So its a valid Python syntax but not valid for Python type checkers as they don't expect builtins as valid types.

And yeah the correct way to do same even if you didn't meant to ask this would be to use typing.Any as like:

import typing

def echo(msg: typing.Any) -> None:
    print(str(msg))

Upvotes: 1

jsbueno
jsbueno

Reputation: 110311

any as the Pythonbuilt-in any is a function. The Any that should be used in annotations is typing.Any - which is an annotation marker denoting any possible object.

Usually: the annotation marks should be made with straight out classes, or other specialized objects composed through the typing library.

Upvotes: 2

Will Da Silva
Will Da Silva

Reputation: 7040

I believe you intend for msg to be any type. The correct code for that would be:

from typing import Any

def echo(msg: Any) -> None:
    print(str(msg))

See: https://docs.python.org/3/library/typing.html#typing.Any

In general type annotations should be made with classes and objects from the built-in typing library, rather than functions like any.

Upvotes: 1

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