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Use with_annotated decorator with custom types for allow easy type conversion #1688
Description
Feature Request
When using the argparse approach (with_argparse decorator), the type argument of add_argument can be used for non-basic type conversion (see for example). The same is not possible when using the with_annotated decorator.
Possible design for a solution
Either allow custom types (as Typer does — see custom types) and make a best-effort type conversion for arbitrary annotations, or add an additional parameter to Option and Argument (for example conversion) that enables a two-step type conversion approach.
Activity
KelvinChung2000 commentedon Jun 10, 2026
I will likely add a "converter" option. I am considering forbidding the use of the
typeargument within the metadata, since this kind of adds a chance of shooting yourself by accident, like doinga: Annotated[str, Argument(type=int)]which does not make sense.neoniobium commentedon Jun 10, 2026
Forbidding the use of the
typeargument within the metadata seems reasonable to me — I actually wondered about it while testing the decorator.