signals

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
+## Unreleased
+
+### Added
+
+- Added `immediate` switch to `Signal.publish`
+
 ## [0.63.3] - 2024-05-24
 
 ### Fixed

src/textual/dom.py

@@ -1505,7 +1505,7 @@ def refresh_bindings(self) -> None:
         See [actions](/guide/actions#dynamic-actions) for how to use this method.
 
         """
-        self.call_later(self.screen.refresh_bindings)
+        self.screen.refresh_bindings()
 
     async def action_toggle(self, attribute_name: str) -> None:
         """Toggle an attribute on the node.

src/textual/message_pump.py

@@ -245,7 +245,7 @@ def app(self) -> "App[object]":
             return node
 
     @property
-    def _is_linked_to_app(self) -> bool:
+    def is_attached(self) -> bool:
         """Is this node linked to the app through the DOM?"""
         node: MessagePump | None = self
 
@@ -275,19 +275,6 @@ def log(self) -> Logger:
         """
         return self.app._logger
 
-    @property
-    def is_attached(self) -> bool:
-        """Is the node attached to the app via the DOM?"""
-        from .app import App
-
-        node = self
-
-        while not isinstance(node, App):
-            if node._parent is None:
-                return False
-            node = node._parent
-        return True
-
     def _attach(self, parent: MessagePump) -> None:
         """Set the parent, and therefore attach this node to the tree.
 

src/textual/screen.py

@@ -739,7 +739,9 @@ def _extend_compose(self, widgets: list[Widget]) -> None:
 
     def _on_mount(self, event: events.Mount) -> None:
         """Set up the tooltip-clearing signal when we mount."""
-        self.screen_layout_refresh_signal.subscribe(self, self._maybe_clear_tooltip)
+        self.screen_layout_refresh_signal.subscribe(
+            self, self._maybe_clear_tooltip, immediate=True
+        )
 
     async def _on_idle(self, event: events.Idle) -> None:
         # Check for any widgets marked as 'dirty' (needs a repaint)

src/textual/signal.py

@@ -52,25 +52,45 @@ def __rich_repr__(self) -> rich.repr.Result:
         yield "name", self._name
         yield "subscriptions", list(self._subscriptions.keys())
 
-    def subscribe(self, node: MessagePump, callback: SignalCallbackType) -> None:
+    def subscribe(
+        self,
+        node: MessagePump,
+        callback: SignalCallbackType,
+        immediate: bool = False,
+    ) -> None:
         """Subscribe a node to this signal.
 
         When the signal is published, the callback will be invoked.
 
         Args:
             node: Node to subscribe.
             callback: A callback function which takes a single argument and returns anything (return type ignored).
+            immediate: Invoke the callback immediately on publish if `True`, otherwise post it to the DOM node to be
+                called once existing messages have been processed.
 
         Raises:
             SignalError: Raised when subscribing a non-mounted widget.
         """
+
         if not node.is_running:
             raise SignalError(
                 f"Node must be running to subscribe to a signal (has {node} been mounted)?"
             )
+
+        if immediate:
+
+            def signal_callback(data: object):
+                """Invoke the callback immediately."""
+                callback(data)
+
+        else:
+
+            def signal_callback(data: object):
+                """Post the callback to the node, to call at the next opertunity."""
+                node.call_next(callback, data)
+
         callbacks = self._subscriptions.setdefault(node, [])
-        if callback not in callbacks:
-            callbacks.append(callback)
+        callbacks.append(signal_callback)
 
     def unsubscribe(self, node: MessagePump) -> None:
         """Unsubscribe a node from this signal.

src/textual/widget.py

@@ -934,7 +934,7 @@ def mount(
             Only one of ``before`` or ``after`` can be provided. If both are
             provided a ``MountError`` will be raised.
         """
-        if not self._is_linked_to_app:
+        if not self.is_attached:
             raise MountError(f"Can't mount widget(s) before {self!r} is mounted")
         # Check for duplicate IDs in the incoming widgets
         ids_to_mount = [widget.id for widget in widgets if widget.id is not None]
@@ -1126,7 +1126,7 @@ async def recompose(self) -> None:
         if self._parent is not None:
             async with self.batch():
                 await self.query("*").exclude(".-textual-system").remove()
-                if self._is_linked_to_app:
+                if self.is_attached:
                     await self.mount_all(compose(self))
 
     def _post_register(self, app: App) -> None:

src/textual/widgets/_footer.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 from collections import defaultdict
+from typing import TYPE_CHECKING
 
 import rich.repr
 from rich.text import Text
@@ -11,6 +12,9 @@
 from ..reactive import reactive
 from ..widget import Widget
 
+if TYPE_CHECKING:
+    from ..screen import Screen
+
 
 @rich.repr.auto
 class FooterKey(Widget):
@@ -157,9 +161,9 @@ def compose(self) -> ComposeResult:
             )
 
     def on_mount(self) -> None:
-        def bindings_changed(screen) -> None:
+        async def bindings_changed(screen: Screen) -> None:
             if screen is self.screen:
-                self.call_next(self.recompose)
+                await self.recompose()
 
         self.screen.bindings_updated_signal.subscribe(self, bindings_changed)
 

tests/test_suspend.py

@@ -48,8 +48,8 @@ def on_resume(self, _) -> None:
             calls.add("resume signal")
 
         def on_mount(self) -> None:
-            self.app_suspend_signal.subscribe(self, self.on_suspend)
-            self.app_resume_signal.subscribe(self, self.on_resume)
+            self.app_suspend_signal.subscribe(self, self.on_suspend, immediate=True)
+            self.app_resume_signal.subscribe(self, self.on_resume, immediate=True)
 
     async with SuspendApp(driver_class=HeadlessSuspendDriver).run_test(
         headless=False