Group Validators

Cyclopts has some builtin common group validators in the cyclopts.validators module.

LimitedChoice

Limits the number of specified arguments within the group. Most commonly used for mutually-exclusive arguments (default behavior).

from cyclopts import App, Group, Parameter, validators
from typing import Annotated

app = App()

vehicle = Group(
    "Vehicle (choose one)",
    default_parameter=Parameter(negative=""),  # Disable "--no-" flags
    validator=validators.LimitedChoice(),  # Mutually Exclusive Options
)


@app.default
def main(
    *,
    car: Annotated[bool, Parameter(group=vehicle)] = False,
    truck: Annotated[bool, Parameter(group=vehicle)] = False,
):
    if car:
        print("I'm driving a car.")
    if truck:
        print("I'm driving a truck.")


app()

$ python drive.py --help
Usage: main COMMAND [OPTIONS]

╭─ Vehicle (choose one) ────────────────────────────────────────────────╮
│ --car    [default: False]                                             │
│ --truck  [default: False]                                             │
╰───────────────────────────────────────────────────────────────────────╯
╭─ Commands ────────────────────────────────────────────────────────────╮
│ --help,-h  Display this message and exit.                             │
│ --version  Display application version.                               │
╰───────────────────────────────────────────────────────────────────────╯

$ python drive.py --car
I'm driving a car.

$ python drive.py --car --truck
╭─ Error ───────────────────────────────────────────────────────────────╮
│ Mutually exclusive arguments: {--car, --truck}                        │
╰───────────────────────────────────────────────────────────────────────╯

See the LimitedChoice docs for more info.