Computed methods aren't called from mutate_reactive

[Banbury]

Computed methods are not called if a reactive is updated with mutate_reactive.

Example:

from textual.app import App, ComposeResult
from textual.widgets import Static, Button
from textual.reactive import reactive

class TestWidget(Static):
    msg: reactive[list[str]] = reactive(list, recompose=True)
    count: reactive(0)

    def compute_count(self):
        return len(self.msg)

    def compose(self) -> ComposeResult:
        yield Static(" ".join(self.msg))


class TestApp(App):
    msg: reactive[list[str]] = reactive(list, recompose=True)
    def compose(self) -> ComposeResult:
        yield TestWidget().data_bind(TestApp.msg)
        yield Button("Click me", id="button")

    def on_button_pressed(self, event: Button.Pressed) -> None:
        self.msg.append("Hello")
        self.mutate_reactive(TestApp.msg)

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

Place a breakpoint in compute_count and run the app. Press the button. The execution doesn't stop at the breakpoint.

[github-actions]

We found the following entry in the FAQ which you may find helpful:

• No widget called TextLog

Feel free to close this issue if you found an answer in the FAQ. Otherwise, please give us a little time to review.

This is an automated reply, generated by FAQtory

[TomJGooding]

From a quick glance, it looks like you're not actually creating a reactive here - try changing : to =?

count: reactive(0)

[willmcgugan]

@Banbury Tom is correct. If you make this change, then the compute method is called:

count = reactive(0)

[github-actions]

Don't forget to star the repository!

Follow @textualizeio for Textual updates.

[Banbury]

Textual is a great framework. But reactives and data binding are confusing.