How do I pass arguments to an app? - Textual

When creating your App class, override __init__ as you would when inheriting normally. For example:

python

from textual.app import App, ComposeResult
from textual.widgets import Static

class Greetings(App[None]):

    def __init__(self, greeting: str="Hello", to_greet: str="World") -> None:
        self.greeting = greeting
        self.to_greet = to_greet
        super().__init__()

    def compose(self) -> ComposeResult:
        yield Static(f"{self.greeting}, {self.to_greet}")

Then the app can be run, passing in various arguments; for example:

python

# Running with default arguments.
Greetings().run()

# Running with a keyword argument.
Greetings(to_greet="davep").run()

# Running with both positional arguments.
Greetings("Well hello", "there").run()