Typer

Behind the scenes, Jeeves relies upon Typer.

Every function in jeeves.py is converted into a Typer command. Just as if you did:

from typer import Typer

app = Typer()

@app.command()
def hi(name: str):
    """…"""

if __name__ == '__main__':
    app()

• That's one way how Jeeves reduces the boilerplate;
• The other way is to expose all those commands via the j shortcut.

Nonetheless, you still can use most Typer features, such as:

• define typer.Argument's and typer.Option's for your commands,
• validate user input using type hints,
• and much more.

Example: Use Typer features directly

jeeves.py

from enum import Enum, auto

import typer


class GreetingStyle(Enum):
    """Style of the greeting."""

    ENGLISH = 'en'
    ITALIAN = 'it'


def hi(
    name: str = typer.Argument(
        ...,
        help='Name of the one we would like to greet.',
        envvar='NAME_TO_GREET',
    ),
    style: GreetingStyle = typer.Option(
        GreetingStyle.ENGLISH,
        help='Style of the greeting.',
    ),
):
    """Greet the user."""
    greeting = {
        GreetingStyle.ENGLISH: 'Hello',
        GreetingStyle.ITALIAN: 'Buongiorno',
    }[style]

    typer.echo(f'{greeting} {name}!')

⇒

↦ j hi --help

 Usage: j hi [OPTIONS] NAME                                                     

 Greet the user.                                                                

╭─ Arguments ──────────────────────────────────────────────────────────────────╮
│ *    name      TEXT  Name of the one we would like to greet.                 │
│                      [env var: NAME_TO_GREET]                                │
│                      [default: None]                                         │
│                      [required]                                              │
╰──────────────────────────────────────────────────────────────────────────────╯
╭─ Options ────────────────────────────────────────────────────────────────────╮
│ --style        [en|it]  Style of the greeting.                               │
│                         [default: GreetingStyle.ENGLISH]                     │
│ --help                  Show this message and exit.                          │
╰──────────────────────────────────────────────────────────────────────────────╯

Example: Typer Validation

↦ j hi --style de

(stdout is empty)

Error

Usage: j hi [OPTIONS] NAME
Try 'j hi --help' for help.
╭─ Error ──────────────────────────────────────────────────────────────────────╮
│ Invalid value for '--style': 'de' is not one of 'en', 'it'.                  │
╰──────────────────────────────────────────────────────────────────────────────╯