Ability to specify choices for help text independently of parameter type

[mikenerone]

First Check

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Example Code

from typing import Annotated

import typer


def _get_list_of_currently_installed_log_output_plugin_names() -> list[str]:
    return ["file", "datadog", "loggly"]  # Real implementation is dynamic


def main(log_output: Annotated[str, typer.Option(help_choices=_get_list_of_currently_installed_log_output_plugin_names()]) -> None:
    typer.echo(f"Log output plugin specification is {log_output!r}")


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

Description

I have a need to be able to display some choices for a parameter in help text, but not actually enforce those choices. My particular use case for this is that my app uses plugins extensively, and the user needs to be able to specify which plugins to use for specific purposes on the command line. The problem is that plugins optionally take arguments, which the user can provide using a colon-separated syntax. My specific example here is letting the user select where to send logs, and the available plugins might be "file", "datadog", and "loggly", where each accepts appropriate arguments.

For this case, what I want is for help output for this parameter to display the choices {file|datadog|loggly}, but since the actual type is just str, the choices are unenforced by typer, so the following command would be allowed:

<this-command> --log-output file:/path/to/file.log

I understand that it would be left up to me to check the true validity of the string and raise the appropriate error for typer if it's wrong. Also, using an Enum would be fine if we must, although IMO even the typical, existing uses of choices should support simple lists instead of Enums, but that's a separate discussion. :)

Operating System

Linux

Operating System Details

No response

Typer Version

0.9.0

Python Version

3.12.1

Additional Context

No response

[mikenerone]

I ended up solving this by creating my own click type, that specifically handles my plugin specification syntax. Unfortunately it's in a proprietary codebase, so I can't share it as an example, but it's relatively straightforward to do so. In the click codebase, look through click/types.py for many examples.