How can I create an annotated argument without a default value?

[justinclloyd]

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Example Code

# First example on https://typer.tiangolo.com/tutorial/options/required/
import typer
from typing_extensions import Annotated

def main(name: str, lastname: Annotated[str, typer.Option()]):
    print(f"Hello {name} {lastname}")

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

Description

The example code doesn't work, throwing the following exception saying that Option() needs a default argument.

Traceback (most recent call last):
  File "./t.py", line 6, in <module>
    def main(name: str, lastname: Annotated[str, typer.Option()]):
TypeError: Option() missing 1 required positional argument: 'default'

Ultimately, I'm trying to create a Typer command that takes a required pathlib.Path argument for which there is no sane default value. I could make one up, even use a fake location, but I feel this should be possible.

Operating System

Linux

Operating System Details

Ubuntu 20.04

Typer Version

0.4.2

Python Version

3.8.10

Additional Context

No response

[pmav99]

1. You wrote that you use version 0.4.2. AFAIK version 0.4.2 doesn't support Annotated, yet you ask for Annotated. If you want to use Annotated I would suggest that you upgrade to 0.9.0+
2. To answer the question of the title, an example of Annotated argument with a default value (i.e. an optional argument) can be found in the docs
3. You wrote:

a Typer command that takes a required pathlib.Path argument for which there is no sane default value.

Probably some terminology miscommunication here, but If the argument has a default value, then it is an optional argument, is it not?