Option optional value doesn't work because is_flag is not passed to click properly

[iurisilvio]

First Check

• I added a very descriptive title here.
• I used the GitHub search to find a similar question 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 tutorials 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(
    foo: str = typer.Option(is_flag=False, flag_value="flag", default="default"),
):
    print(f"Hello {foo}")

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

Description

Click support options with optional values.

I'd expect Typer to work the same way, because it expose both is_flag and flag_value, but it fails.

I would expect this:

$ python foo.py
Hello default
$ python foo.py --foo
Hello flag
$ python foo.py --foo value
Hello value

But this is what I get:

$ python foo.py
Hello flag
$ python foo.py --foo
Hello flag
$ python foo.py --foo value
Usage: foo.py [OPTIONS]
Try 'foo.py --help' for help.
Error: Got unexpected extra argument (value)

It works nice with #872.

Operating System

macOS

Operating System Details

No response

Typer Version

0.12.3

Python Version

Python 3.11.9

Additional Context

No response

[tiangolo]

Thanks for pointing this out! I realized it doesn't make sense to have that parameter when it's not really supported in Typer. And I consider it's better to have only the boot type annotation, and if the application code needs a string, then it can check if the bool is True or False, instead of having it as part of the library.

Removing the parameter was done here: #987

[alanwilter]

Heavens, please show an example of how to use your approach and not the click one!

I need to handle --my_arg whose default is 'hello':

app
# my_arg is None or False
app --my_arg
# my_arg = hello
app --my_arg bye
# my_arg = bye

[jnu]

+1 for this. It's common to distinguish between these three cases (no option passed, option passed with no argument, and option passed with argument). Doesn't seem like there's a way to do it in Typer right now, which is disappointing.