How to follow a plan action from a view¶

Each action of a plan can have its own button in a view. Pressing the button asks the component's ActionManager for the action, and the view then sets the button from what the plan answers. How presenters run plans explains the states an action goes through.

Prerequisites¶

You need a component that offers a plan declaring actions, and owns the ActionManager the plan waits on. See Actions while a plan runs.

Ask, and follow the answer¶

The view asks with a signal carrying the name of the action and whether the button is pressed, and follows the answer in a slot:

from psygnal import Signal

from redsun import slot
from redsun.engine.actions import ActionState


class MyView(QWidget):
    sig_action_request = Signal(str, bool)

    def ask(self, name: str) -> None:
        self.sig_action_request.emit(name, True)

    def ask_or_release(self, checked: bool, name: str) -> None:
        self.sig_action_request.emit(name, checked)

    @slot
    def on_action_changed(self, name: str, state: str) -> None:
        button = self.widget.action_buttons[name]
        match state:
            case ActionState.IDLE:
                button.setEnabled(False)
                button.release()
            case ActionState.OFFERED:
                button.setEnabled(True)
            case ActionState.RUNNING:
                button.setEnabled(button.isCheckable())

ask and ask_or_release are the action_clicked_callback and action_toggled_callback of the plan widget, here self.widget. release shows a button as released without emitting toggled. Unchecking the button would emit it, and the view would then ask to end an action that has already ended.

Link the view and the component¶

In wire:

class MyApp(QtSession):
    ctrl: AsPresenter[MyController]
    panel: AsView[MyView]

    def wire(self) -> Iterator[Link]:
        yield self.panel.sig_action_request, self.ctrl.actions.request
        yield self.ctrl.actions.sig_changed, self.panel.on_action_changed

The session records an ActionManager under the name of the component holding it, so it records the two links as panel.sig_action_request -> ctrl.request and ctrl.sig_changed -> panel.on_action_changed. See Inspect what is connected.