Basic dynamic textual app

things.py

from textual.app import App, ComposeResult
from textual.containers import Container
from textual.reactive import reactive
from textual.widgets import Static


class Thing(Static):
    def __init__( self, text ) -> None:
        self._text = text
        super().__init__()

    def compose(self) -> ComposeResult:
        yield Static(self._text)

class ThingApp(App):
  BINDINGS = [ 
    ("a", "add_thing", "Add Thing"),
    ("d", "remove_thing", "Remove Thing")
  ]

  thing_count = reactive(1)
 
  def compose(self) -> ComposeResult:
    yield Container(Thing("thing_1"), id="things")
    yield Container(Static("Single thing", id="text"))

  def action_add_thing(self) -> None:
    self.thing_count += 1
    new_thing = Thing(f"thing_{self.thing_count}")
    self.query_one("#things").mount(new_thing)

  def watch_thing_count(self, thing_count) -> None:
    self.query_one("#text", Static).update(f"{self.thing_count} things")
        
  def action_remove_thing(self) -> None:
    things = self.query("Thing")
    if len(things) > 0:
      things.last().remove()
      self.thing_count -= 1


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