Message posting clean-up

CHANGELOG.md

@@ -33,6 +33,15 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 - Clicking a non focusable widget focus ancestors https://github.com/Textualize/textual/pull/4236
 - BREAKING: widget class names must start with a capital letter or an underscore `_` https://github.com/Textualize/textual/pull/4252
+- BREAKING: for many widgets, messages are now sent when programmatic changes that mirror user input are made https://github.com/Textualize/textual/pull/4256
+  - Changed `Collapsible`
+  - Changed `Markdown`
+  - Changed `Select`
+  - Changed `SelectionList`
+  - Changed `TabbedContent`
+  - Changed `Tabs`
+  - Changed `TextArea`
+  - Changed `Tree`
 
 ## [0.52.1] - 2024-02-20
 

src/textual/widgets/_collapsible.py

@@ -92,7 +92,7 @@ def _watch_collapsed(self, collapsed: bool) -> None:
 class Collapsible(Widget):
     """A collapsible container."""
 
-    collapsed = reactive(True)
+    collapsed = reactive(True, init=False)
     title = reactive("Toggle")
 
     DEFAULT_CSS = """
@@ -194,14 +194,14 @@ def __init__(
     def _on_collapsible_title_toggle(self, event: CollapsibleTitle.Toggle) -> None:
         event.stop()
         self.collapsed = not self.collapsed
-        if self.collapsed:
-            self.post_message(self.Collapsed(self))
-        else:
-            self.post_message(self.Expanded(self))
 
     def _watch_collapsed(self, collapsed: bool) -> None:
         """Update collapsed state when reactive is changed."""
         self._update_collapsed(collapsed)
+        if self.collapsed:
+            self.post_message(self.Collapsed(self))
+        else:
+            self.post_message(self.Expanded(self))
 
     def _update_collapsed(self, collapsed: bool) -> None:
         """Update children to match collapsed state."""

src/textual/widgets/_markdown.py

@@ -934,7 +934,9 @@ def update(self, markdown: str) -> AwaitComplete:
                     (stack[-1]._blocks if stack else output).append(external)
 
         self.post_message(
-            Markdown.TableOfContentsUpdated(self, self._table_of_contents)
+            Markdown.TableOfContentsUpdated(self, self._table_of_contents).set_sender(
+                self
+            )
         )
         markdown_block = self.query("MarkdownBlock")
 

src/textual/widgets/_select.py

@@ -240,7 +240,9 @@ class Select(Generic[SelectType], Vertical, can_focus=True):
     """True to show the overlay, otherwise False."""
     prompt: var[str] = var[str]("Select")
     """The prompt to show when no value is selected."""
-    value: var[SelectType | NoSelection] = var[Union[SelectType, NoSelection]](BLANK)
+    value: var[SelectType | NoSelection] = var[Union[SelectType, NoSelection]](
+        BLANK, init=False
+    )
     """The value of the selection.
 
     If the widget has no selection, its value will be [`Select.BLANK`][textual.widgets.Select.BLANK].
@@ -459,6 +461,7 @@ def _watch_value(self, value: SelectType | NoSelection) -> None:
                         select_overlay.highlighted = index
                         select_current.update(prompt)
                         break
+            self.post_message(self.Changed(self, value))
 
     def compose(self) -> ComposeResult:
         """Compose Select with overlay and current value."""
@@ -509,7 +512,6 @@ def _update_selection(self, event: SelectOverlay.UpdateSelection) -> None:
         value = self._options[event.option_index][1]
         if value != self.value:
             self.value = value
-            self.post_message(self.Changed(self, value))
 
         async def update_focus() -> None:
             """Update focus and reset overlay."""

src/textual/widgets/_selection_list.py

@@ -252,14 +252,19 @@ def __init__(
         """Tracking of which values are selected."""
         self._send_messages = False
         """Keep track of when we're ready to start sending messages."""
+        options = [self._make_selection(selection) for selection in selections]
         super().__init__(
-            *[self._make_selection(selection) for selection in selections],
+            *options,
             name=name,
             id=id,
             classes=classes,
             disabled=disabled,
             wrap=False,
         )
+        self._values: dict[SelectionType, int] = {
+            option.value: index for index, option in enumerate(options)
+        }
+        """Keeps track of which value relates to which option."""
 
     @property
     def selected(self) -> list[SelectionType]:
@@ -285,7 +290,20 @@ def _message_changed(self) -> None:
             messages.
         """
         if self._send_messages:
-            self.post_message(self.SelectedChanged(self))
+            self.post_message(self.SelectedChanged(self).set_sender(self))
+
+    def _message_toggled(self, option_index: int) -> None:
+        """Post a message that an option was toggled, where appropriate.
+
+        Note:
+            A message will only be sent if `_send_messages` is `True`. This
+            makes this safe to call before the widget is ready for posting
+            messages.
+        """
+        if self._send_messages:
+            self.post_message(
+                self.SelectionToggled(self, option_index).set_sender(self)
+            )
 
     def _apply_to_all(self, state_change: Callable[[SelectionType], bool]) -> Self:
         """Apply a selection state change to all selection options in the list.
@@ -306,9 +324,9 @@ def _apply_to_all(self, state_change: Callable[[SelectionType], bool]) -> Self:
         changed = False
 
         # Next we run through everything and apply the change, preventing
-        # the changed message because the caller really isn't going to be
-        # expecting a message storm from this.
-        with self.prevent(self.SelectedChanged):
+        # the toggled and changed messages because the caller really isn't
+        # going to be expecting a message storm from this.
+        with self.prevent(self.SelectedChanged, self.SelectionToggled):
             for selection in self._options:
                 changed = (
                     state_change(cast(Selection[SelectionType], selection).value)
@@ -416,6 +434,7 @@ def _toggle(self, value: SelectionType) -> bool:
             self._deselect(value)
         else:
             self._select(value)
+        self._message_toggled(self._values[value])
         return True
 
     def toggle(self, selection: Selection[SelectionType] | SelectionType) -> Self:
@@ -593,7 +612,6 @@ def _on_option_list_option_selected(self, event: OptionList.OptionSelected) -> N
         """
         event.stop()
         self._toggle_highlighted_selection()
-        self.post_message(self.SelectionToggled(self, event.option_index))
 
     def get_option_at_index(self, index: int) -> Selection[SelectionType]:
         """Get the selection option at the given index.
@@ -632,7 +650,9 @@ def _remove_option(self, index: int) -> None:
         Raises:
             IndexError: If there is no selection option of the given index.
         """
-        self._deselect(self.get_option_at_index(index).value)
+        option = self.get_option_at_index(index)
+        self._deselect(option.value)
+        del self._values[option.value]
         return super()._remove_option(index)
 
     def add_options(
@@ -679,6 +699,15 @@ def add_options(
                 raise SelectionError(
                     "Only Selection or a prompt/value tuple is supported in SelectionList"
                 )
+
+        # Add the new items to the value mappings.
+        self._values.update(
+            {
+                option.value: index
+                for index, option in enumerate(cleaned_options, start=self.option_count)
+            }
+        )
+
         return super().add_options(cleaned_options)
 
     def add_option(
@@ -711,4 +740,5 @@ def clear_options(self) -> Self:
             The `SelectionList` instance.
         """
         self._selected.clear()
+        self._values.clear()
         return super().clear_options()

src/textual/widgets/_tabbed_content.py

@@ -466,16 +466,12 @@ def remove_pane(self, pane_id: str) -> AwaitComplete:
             # other means; so allow that to be a no-op.
             pass
 
-        async def _remove_content(cleared_message: TabbedContent.Cleared) -> None:
+        async def _remove_content() -> None:
             await gather(*removal_awaitables)
             if self.tab_count == 0:
-                self.post_message(cleared_message)
+                self.post_message(self.Cleared(self).set_sender(self))
 
-        # Note that I create the Cleared message out here, rather than in
-        # _remove_content, to ensure that the message's internal
-        # understanding of who the sender is is correct.
-        # https://github.com/Textualize/textual/issues/2750
-        return AwaitComplete(_remove_content(self.Cleared(self)))
+        return AwaitComplete(_remove_content())
 
     def clear_panes(self) -> AwaitComplete:
         """Remove all the panes in the tabbed content.
@@ -489,15 +485,11 @@ def clear_panes(self) -> AwaitComplete:
             self.get_child_by_type(ContentSwitcher).remove_children(),
         )
 
-        async def _clear_content(cleared_message: TabbedContent.Cleared) -> None:
+        async def _clear_content() -> None:
             await await_clear
-            self.post_message(cleared_message)
+            self.post_message(self.Cleared(self).set_sender(self))
 
-        # Note that I create the Cleared message out here, rather than in
-        # _clear_content, to ensure that the message's internal
-        # understanding of who the sender is is correct.
-        # https://github.com/Textualize/textual/issues/2750
-        return AwaitComplete(_clear_content(self.Cleared(self)))
+        return AwaitComplete(_clear_content())
 
     def compose_add_child(self, widget: Widget) -> None:
         """When using the context manager compose syntax, we want to attach nodes to the switcher.

src/textual/widgets/_tabs.py

@@ -797,7 +797,7 @@ def hide(self, tab_id: str) -> Tab:
             next_tab = self._next_active
             self.active = next_tab.id or "" if next_tab else ""
         tab_to_hide.add_class("-hidden")
-        self.post_message(self.TabHidden(self, tab_to_hide))
+        self.post_message(self.TabHidden(self, tab_to_hide).set_sender(self))
         self.call_after_refresh(self._highlight_active)
         return tab_to_hide
 
@@ -820,7 +820,7 @@ def show(self, tab_id: str) -> Tab:
             raise self.TabError(f"There is no tab with ID {tab_id!r} to show.")
 
         tab_to_show.remove_class("-hidden")
-        self.post_message(self.TabShown(self, tab_to_show))
+        self.post_message(self.TabShown(self, tab_to_show).set_sender(self))
         if not self.active:
             self._activate_tab(tab_to_show)
         self.call_after_refresh(self._highlight_active)

src/textual/widgets/_text_area.py

@@ -92,33 +92,33 @@ class TextArea(ScrollView):
     height: 1fr;
     border: tall $background;
     padding: 0 1;
-    
+
     & .text-area--gutter {
         color: $text 40%;
     }
-    
+
     & .text-area--cursor-gutter {
         color: $text 60%;
         background: $boost;
         text-style: bold;
     }
-    
+
     & .text-area--cursor-line {
        background: $boost;
     }
-    
+
     & .text-area--selection {
         background: $accent-lighten-1 40%;
     }
-    
+
     & .text-area--matching-bracket {
         background: $foreground 30%;
     }
-    
+
     &:focus {
         border: tall $accent;
     }
-    
+
     &:dark {
         .text-area--cursor {
            color: $text 90%;
@@ -128,11 +128,11 @@ class TextArea(ScrollView):
             background: $warning-darken-1;
         }
     }
-    
+
     &:light {
         .text-area--cursor {
             color: $text 90%;
-            background: $foreground 70%;   
+            background: $foreground 70%;
         }
         &.-read-only .text-area--cursor {
             background: $warning-darken-1;
@@ -151,9 +151,9 @@ class TextArea(ScrollView):
     }
     """
     `TextArea` offers some component classes which can be used to style aspects of the widget.
-    
+
     Note that any attributes provided in the chosen `TextAreaTheme` will take priority here.
-    
+
     | Class | Description |
     | :- | :- |
     | `text-area--cursor` | Target the cursor. |
@@ -313,9 +313,9 @@ class TextArea(ScrollView):
 
     read_only: Reactive[bool] = reactive(False)
     """True if the content is read-only.
-    
+
     Read-only means end users cannot insert, delete or replace content.
-    
+
     The document can still be edited programmatically via the API.
     """
 
@@ -883,6 +883,7 @@ def load_text(self, text: str) -> None:
         """
         self.history.clear()
         self._set_document(text, self.language)
+        self.post_message(self.Changed(self).set_sender(self))
 
     def _on_resize(self) -> None:
         self._rewrap_and_refresh_virtual_size()

src/textual/widgets/_tree.py

@@ -215,7 +215,7 @@ def _expand(self, expand_all: bool) -> None:
         """
         self._expanded = True
         self._updates += 1
-        self._tree.post_message(Tree.NodeExpanded(self))
+        self._tree.post_message(Tree.NodeExpanded(self).set_sender(self._tree))
         if expand_all:
             for child in self.children:
                 child._expand(expand_all)
@@ -248,7 +248,7 @@ def _collapse(self, collapse_all: bool) -> None:
         """
         self._expanded = False
         self._updates += 1
-        self._tree.post_message(Tree.NodeCollapsed(self))
+        self._tree.post_message(Tree.NodeCollapsed(self).set_sender(self._tree))
         if collapse_all:
             for child in self.children:
                 child._collapse(collapse_all)

tests/select/test_changed_message.py

@@ -55,3 +55,13 @@ async def test_same_selection_does_not_post_message():
         await pilot.click(SelectOverlay, offset=(2, 3))
         await pilot.pause()
         assert len(app.changed_messages) == 1
+
+
+async def test_setting_value_posts_message() -> None:
+    """Setting the value of a Select should post a message."""
+
+    async with (app := SelectApp()).run_test() as pilot:
+        assert len(app.changed_messages) == 0
+        app.query_one(Select).value = 2
+        await pilot.pause()
+        assert len(app.changed_messages) == 1

tests/selection_list/test_selection_messages.py

@@ -28,17 +28,21 @@ def compose(self) -> ComposeResult:
     @on(SelectionList.SelectedChanged)
     def _record(
         self,
-        event: OptionList.OptionMessage
-        | SelectionList.SelectionMessage
-        | SelectionList.SelectedChanged,
+        event: (
+            OptionList.OptionMessage
+            | SelectionList.SelectionMessage
+            | SelectionList.SelectedChanged
+        ),
     ) -> None:
         assert event.control == self.query_one(SelectionList)
         self.messages.append(
             (
                 event.__class__.__name__,
-                event.selection_index
-                if isinstance(event, SelectionList.SelectionMessage)
-                else None,
+                (
+                    event.selection_index
+                    if isinstance(event, SelectionList.SelectionMessage)
+                    else None
+                ),
             )
         )
 
@@ -71,6 +75,7 @@ async def test_toggle() -> None:
         assert pilot.app.messages == [
             ("SelectionHighlighted", 0),
             ("SelectedChanged", None),
+            ("SelectionToggled", 0),
         ]