dynamic bindings

[willmcgugan]

Stab at dynamic bindings

Wedding present for @darrenburns

[TomJGooding]

Just a few suggestions where I spotted some typos in the docs - hope you don't mind!

[TomJGooding]

Sorry also just a quick question which I've seen asked before relating to dynamic bindings.

What would be the most practical way with this new feature of hiding bindings when an Input or TextArea is currently focussed? Here's a contrived example where lots of bindings obviously won't work while the Input is focussed.

from textual.app import App, ComposeResult
from textual.widgets import Input, Footer, Button


class ExampleApp(App):
    CSS = """
    Screen {
        align: center middle;
    }

    Input {
        width: 16;
    }
    """

    BINDINGS = [
        ("a", "notify_binding('a')", "A"),
        ("b", "notify_binding('b')", "B"),
        ("c", "notify_binding('c')", "C"),
        ("f1", "notify_binding('F1')", "F1"),
        ("f2", "notify_binding('F2')", "F2"),
        ("f3", "notify_binding('F3')", "F3"),
    ]

    def compose(self) -> ComposeResult:
        yield Button()
        yield Input(placeholder="Input")
        yield Footer()

    def action_notify_binding(self, key: str) -> None:
        self.notify(f"You pressed {key}")


if __name__ == "__main__":
    app = ExampleApp()
    app.run()

[TomJGooding]

I wonder if an exception should be added for Ctrl+c to quit the app, and maybe other default actions? If you wanted to hide all (custom) bindings when a particular widget was focussed for example, you could easily forget to add this check.

[darrenburns]

😍

[willmcgugan]

Sorry also just a quick question which I've seen asked before relating to dynamic bindings.

What would be the most practical way with this new feature of hiding bindings when an Input or TextArea is currently focussed? Here's a contrived example where lots of bindings obviously won't work while the Input is focussed.

The issue there is that inputs capture most keys with the Key event, which bypasses bindings.

You could do the following:

    def check_action(self, name, params):
        if name == "notify_binding" and isinstance(self.focused, Input):
            return False
        return True

But that does mean you would have to modify the app. Ideally there would be a mechanism for the widget itself to declare it will capture those keys.

[willmcgugan]

I wonder if an exception should be added for Ctrl+c to quit the app, and maybe other default actions? If you wanted to hide all (custom) bindings when a particular widget was focussed for example, you could easily forget to add this check.

I can't see that being much of an issue. As long as you default to return True. But maybe I have misunderstood. Can you give me some example code?

[TomJGooding]

Perhaps just worth a note in the docs explaining that this also applies to builtin actions?

For example using the Input example above, let's say you had a long list of of 'printable' key bindings you wanted to hide. You might think you could do something like this and then not understand why you can't quit the app:

    def check_action(self, name, params):
        if isinstance(self.focused, Input):
            return False
        return True

[davep]

Glancing over this just now, I wonder if #3690 is at least partially satisfied by this PR.