Default Path value in typer.Option combined with Annotated crashes

[ulrikrasmussen]

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Example Code

#FILE: broken.py
from pathlib import Path
from typing import Annotated
import typer

DEFAULT_CFG = Path.home() / "config.yaml"

def main(config: Annotated[Path, typer.Option(DEFAULT_CFG, "--config", "-c")]):
    typer.echo(f"Using configuration: {config}")

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



#FILE: works.py
from pathlib import Path
import typer

DEFAULT_CFG = Path.home() / "config.yaml"

# Only difference is not using Annotated[]
def main(config: Path = typer.Option(DEFAULT_CFG, "--config", "-c")):
    typer.echo(f"Using configuration: {config}")

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

Description

Running broken.py, I get

[... lots of stack trace ...]
AttributeError: 'PosixPath' object has no attribute 'isidentifier'

Running works.py, I get

Using configuration: /home/ulrik/config.yaml

Operating System

Linux

Operating System Details

No response

Typer Version

0.15.3

Python Version

3.12.3

Additional Context

No response

[ulrikrasmussen]

I found the solution; it is because default values should of course not be passed as the first argument to typer.Option when using Annotated, but instead they should be specified as default values for the method parameter:

from pathlib import Path
from typing import Annotated
import typer

DEFAULT_CFG = Path.home() / "config.yaml"

def main(config: Annotated[Path, typer.Option("--config", "-c") = DEFAULT_CFG]):
    typer.echo(f"Using configuration: {config}")

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