Document how to provide a negative number as an argument

[ricardogsilva]

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

# script name: main.py

import typer

app = typer.Typer()


@app.command()
def failing(value: float):
    print(f"{value=}")
    

@app.command(
    context_settings={"ignore_unknown_options": True}
)
def working_good(value: float):
    print(f"{value=}")
    
    
if __name__ == "__main__":
    app()

Description

Using a negative number as an argument needs some special crafting in order to work.

If you try calling the above with a negative number, you'll get an error like this:

python run main.py failing -5

Usage: main.py failing [OPTIONS] VALUE
Try 'main.py failing --help' for help.
Error

No such option: -5                                                                                                                                                                                                                                                                                                          

The respective click docs mention two strategies:

Option 1 - use --- as a separator

Quoting the click docs:

To solve this, Click does what any POSIX style command line script does, and that is to accept the string -- as a separator for options and arguments. After the -- marker, all further parameters are accepted as arguments.

This option does not seem to work on Typer - I'm not sure whether this is a bug or not - maybe it could be a missing feature?

Option 2 - pass ignore_unknown_options to context

If you don’t like the -- marker, you can set ignore_unknown_options to True to avoid checking unknown options

This does work with Typer, as demonstrated in the code snippet I pasted above, as if you change the invocation to run the working-good command you get:

poetry run main.py working-good -5
value=-5.0

In my opinion the Typer docs should mention this in the CLI Parameter types - Number section - it would have saved me a bunch of time if it did 😉

Operating System

Linux

Operating System Details

No response

Typer Version

0.12.3

Python Version

3.10.12

Additional Context

No response

[danka12324]

Thank you for your message and for the inconsistency found in the Typer documentation. Indeed, there is no mention in the Typer documentation of the need to use the context_settings={"ignore_unknown_options": True} context parameter to correctly handle negative numbers on the command line. I suggest adding this point to the documentation so that other users can also avoid similar difficulties.

Your code example demonstrates the correct way to handle negative numbers on the command line using Typer. If you encounter any other questions or problems, please let me know and I will try to help you.