MethodHandler

Like a Handler, except it calls an unbound method that must be later bound. Example:

class MyWidget: StatelessWidget, HashableWidget {
    func onClick() {}
    static let onClickHandler = MethodHandler(onClick)
    ...
    func build(ctx: BuildContext) -> Widget {
        return Button(
            Button.onClick => MyWidget.onClickHandler.bind(to: self)
        )
}
}