can one change the description of a binding dynamically

[calestyo]

Hey.

I have for example a binding which toggles a state... like between hide/show, and it would be nice if the description indicates this by telling what it currently does.

AFAIU this can't be done via dynamic actions, which merely allow do show/hide/grey-out an action.

I tried everything I can think of... re-binding the same binding via self.bin(), replacing the object in BINDINGS.... but the footer gets never updated, not even when I call self.refresh_bindings() or footer.refresh()

Is there any trick I don't see?

Thanks,
Chris.

[jdfesa]

Dynamic actions can handle this if you use two mutually exclusive actions on the same key, each with its own description. You don't need to mutate the description of one binding:

from textual.app import App, ComposeResult
from textual.binding import Binding
from textual.reactive import reactive
from textual.widgets import Footer, Static


class Demo(App):
    BINDINGS = [
        Binding("d", "show_details", "Show details"),
        Binding("d", "hide_details", "Hide details"),
    ]
    details_visible = reactive(False, bindings=True)

    def compose(self) -> ComposeResult:
        yield Static("Details", id="details")
        yield Footer()

    def on_mount(self) -> None:
        self.query_one("#details", Static).display = self.details_visible

    def watch_details_visible(self, visible: bool) -> None:
        if self.is_mounted:
            self.query_one("#details", Static).display = visible

    def check_action(self, action: str, parameters: tuple[object, ...]):
        if action == "show_details":
            return not self.details_visible
        if action == "hide_details":
            return self.details_visible
        return True

    def action_show_details(self) -> None:
        self.details_visible = True

    def action_hide_details(self) -> None:
        self.details_visible = False


if __name__ == "__main__":
    Demo().run()

Return False, not None, for the inactive action: False removes it from the active bindings; None leaves a disabled binding there. bindings=True refreshes the footer when the state changes. Both behaviors are described in the dynamic-actions documentation.

The rebinding result also makes sense from the implementation: bind() appends, while active_bindings keeps the first eligible binding for a key. Repeatedly adding the same action with a new description doesn't replace that first binding. Changing the class BINDINGS list after initialization isn't the same as changing the instance's binding map.

[mkzung]

Yes, if you swap the Binding in the instance's own bindings map and then call refresh_bindings(). Binding is a frozen dataclass, so make a new one with dataclasses.replace:

from dataclasses import replace

from textual.app import App, ComposeResult
from textual.binding import Binding
from textual.widgets import Footer, Static


class Demo(App):
    BINDINGS = [Binding("d", "toggle_details", "Show details")]

    def compose(self) -> ComposeResult:
        yield Static("Details", id="details")
        yield Footer()

    def on_mount(self) -> None:
        self.query_one("#details").display = False

    def action_toggle_details(self) -> None:
        details = self.query_one("#details")
        details.display = not details.display
        self.set_binding_description("d", "Hide details" if details.display else "Show details")

    def set_binding_description(self, key: str, description: str) -> None:
        bindings = self._bindings.key_to_bindings
        bindings[key] = [replace(b, description=description) for b in bindings[key]]
        self.refresh_bindings()

With textual 8.2.8 the footer toggles "Show details" / "Hide details" on each press of d.

Assign a new list instead of editing in place: BindingsMap.copy() copies only the dict, so the lists are shared with the class. _bindings is private, so pin your textual version.