A watch on a reactive that is declared init=False fires watch method on init

[davep]

Stemming from a question on Discord; consider this code:

from textual.app import App, ComposeResult
from textual.reactive import var
from textual.widgets import Label, Log

class SomeWidget(Label):

    test_1: var[int] = var(0)
    test_2: var[int] = var(0, init=False)

    def watch_test_1(self, was: int, into: int) -> None:
        self.screen.query_one(Log).write_line(f"test_1 {was} -> {into}")

    def watch_test_2(self, was: int, into: int) -> None:
        self.screen.query_one(Log).write_line(f"test_2 {was} -> {into}")

class InitOverrideApp(App[None]):

    def compose(self) -> ComposeResult:
        yield SomeWidget()
        yield Log()

if __name__ == "__main__":
    InitOverrideApp().run()

when run, it correctly logs that test_1 changed, and correctly doesn't log that test_2 changed. Now, if we add a watch on test_2:

from textual.app import App, ComposeResult
from textual.reactive import var
from textual.widgets import Label, Log

class SomeWidget(Label):

    test_1: var[int] = var(0)
    test_2: var[int] = var(0, init=False)

    def watch_test_1(self, was: int, into: int) -> None:
        self.screen.query_one(Log).write_line(f"test_1 {was} -> {into}")

    def watch_test_2(self, was: int, into: int) -> None:
        self.screen.query_one(Log).write_line(f"test_2 {was} -> {into}")

class InitOverrideApp(App[None]):

    def compose(self) -> ComposeResult:
        yield SomeWidget()
        yield Log()

    def on_mount(self) -> None:
        def gndn() -> None:
            return
        self.watch(self.query_one(SomeWidget), "test_2", gndn)

if __name__ == "__main__":
    InitOverrideApp().run()

this appears to override the init=False declared for test_2, and causes SomeWidget.watch_test_2 to fire. This can be worked around by making the watch setup call like this:

        self.watch(self.query_one(SomeWidget), "test_2", gndn, init=False)

but it seems like an unintended consequence that the watch method (SomeWidget.watch_test_2) gets called without that.

[willmcgugan]

The explicit self.watch should only call the method given, and not any reactive watchers.

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