Truthiness of Option(False) should be False

[khaume]

First Check

• I added a very descriptive title to this issue.
• I used the GitHub search to find a similar issue and didn't find it.
• I searched the Typer documentation, with the integrated search.
• I already searched in Google "How to X in Typer" and didn't find any information.
• I already read and followed all the tutorial in the docs and didn't find an answer.
• I already checked if it is not related to Typer but to Click.

Commit to Help

• I commit to help with one of those options 👆

Example Code

import typer

def main(some_flag: bool = typer.Option(False, help="help string")):
    if some_flag:
        print("some_flag was True/Truthy")

if __name__ == "__main__":
    run(main)

Description

If I run this script from as CLI, then it works as expected, i.e. not providing the --some-flag, the code will not enter the if statement.

However, if I call the function from another python function, then some_flag is now an instance of the Option class, and bool(some_flag) is True, which I think is counter-intuitive.

I am aware that I can check for the default value with some_flag.default which would then be False, but I think it would be great if there could be an implementation of the __bool__ method in the Option class, which returns bool(self.default) for these cases.

Operating System

Windows

Operating System Details

No response

Typer Version

0.6.1

Python Version

3.8.2

Additional Context

No response

[tiangolo]

Hey there! Yep, that's because Typer only allowed setting the values as the function parameter "default", in that case, for it to work you would have had to pass the parameters manually when calling the function.

But now there's support for Annotated, to solve exactly this problem 🎉

import typer
from typing_extensions import Annotated

def main(some_flag: Annotated[bool, typer.Option(help="help string")] = False):
    if some_flag:
        print("some_flag was True/Truthy")

if __name__ == "__main__":
    run(main)
    main()

It's available in Typer 0.9.0, just released 🚀