Adding a simpler way to bind reactives when dynamically mounting new widgets

[AliJavidiCS]

Hi. This is a simple request to add simpler way to use data_bind on dynamically mounted widgets. Take a look at the sample code below please.

from textual.app import App, ComposeResult
from textual.widgets import Label
from textual.reactive import reactive
from textual.widget import Widget


class L3(Widget):
    animal_sound = reactive("Meow")

    def compose(self) -> ComposeResult:
        yield Label(self.animal_sound*3)


class L2(Widget):
    animal_sound = reactive("Woof")

    def compose(self) -> ComposeResult:
        yield Label(self.animal_sound*2)
        yield L3()

    def on_focus(self, event: Focus):
        new_L3 = L3()
        new_L3.animal_sound = "Hmmm"
        
        # How Can I bind L3's animal_sound to MainApp's animal sound directly?
        new_L3.data_bind(self.parent.animal_sound) # Would be so great if we could use objects to bind reactives instead of classes
        self.mount(new_L3)


class MainApp(App):
    animal_sound = reactive("Woof")

    def compose(self) -> ComposeResult:
        yield Label("Sorry if this question is dumb")
        yield L2()


MainApp().run()

Thanks in advance!

[willmcgugan]

Using the object rather than the class wouldn't work as the method would get the value of the reactive. There would be no way to tell which reactive it was associated with.

All data_bind method does is create a watcher on a parent, that copies the value to a child. See the docs on data binding for more details.

[AliJavidiCS]

Makes sense.