Namespace IDs for ContentTab in TabbedContent

CHANGELOG.md

@@ -7,6 +7,15 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## Unreleased
 
+### Changed
+
+- The tabs within a `TabbedContent` now prefix their IDs to stop any clash with their associated `TabPane` https://github.com/Textualize/textual/pull/3815
+- Breaking change: `tab` is no longer a `@on` decorator selector for `TabbedContent.TabActivated` -- use `pane` instead https://github.com/Textualize/textual/pull/3815
+
+### Added
+
+- Added a `pane` attribute to `TabbedContent.TabActivated` https://github.com/Textualize/textual/pull/3815
+
 ### Fixed
 
 - Fixed `DataTable.update_cell` not raising an error with an invalid column key https://github.com/Textualize/textual/issues/3335

docs/examples/widgets/tabbed_content_label_color.py

@@ -0,0 +1,25 @@
+from textual.app import App, ComposeResult
+from textual.widgets import Label, TabbedContent, TabPane
+
+
+class ColorTabsApp(App):
+    CSS = """
+    TabbedContent #--content-tab-green {
+        color: green;
+    }
+
+    TabbedContent #--content-tab-red {
+        color: red;
+    }
+    """
+
+    def compose(self) -> ComposeResult:
+        with TabbedContent():
+            with TabPane("Red", id="red"):
+                yield Label("Red!")
+            with TabPane("Green", id="green"):
+                yield Label("Green!")
+
+
+if __name__ == "__main__":
+    ColorTabsApp().run()

docs/widgets/tabbed_content.md

@@ -94,6 +94,30 @@ The following example contains a `TabbedContent` with three tabs.
     --8<-- "docs/examples/widgets/tabbed_content.py"
     ```
 
+## Styling
+
+The `TabbedContent` widget is composed of two main sub-widgets: a
+[`Tabs`](tabs.md) and a [`ContentSwitcher`]((content_switcher.md)); you can
+style them accordingly.
+
+The tabs within the `Tabs` widget will have prefixed IDs; each ID being the
+ID of the `TabPane` the `Tab` is for, prefixed with `--content-tab-`. If you
+wish to style individual tabs within the `TabbedContent` widget you will
+need to use that prefix for the `Tab` IDs.
+
+For example, to create a `TabbedContent` that has red and green labels:
+
+=== "Output"
+
+    ```{.textual path="docs/examples/widgets/tabbed_content_label_color.py"}
+    ```
+
+=== "tabbed_content.py"
+
+    ```python
+    --8<-- "docs/examples/widgets/tabbed_content_label_color.py"
+    ```
+
 ## Reactive Attributes
 
 | Name     | Type  | Default | Description                                                    |

src/textual/widgets/_tabbed_content.py

@@ -6,6 +6,7 @@
 
 from rich.repr import Result
 from rich.text import Text, TextType
+from typing_extensions import Final
 
 from ..app import ComposeResult
 from ..await_complete import AwaitComplete
@@ -26,15 +27,46 @@
 class ContentTab(Tab):
     """A Tab with an associated content id."""
 
-    def __init__(self, label: Text, content_id: str, disabled: bool = False):
+    _PREFIX: Final[str] = "--content-tab-"
+    """The prefix given to the tab IDs."""
+
+    @classmethod
+    def add_prefix(cls, content_id: str) -> str:
+        """Add the prefix to the given ID.
+
+        Args:
+            content_id: The ID to add the prefix to.
+
+        Returns:
+            The ID with the prefix added.
+        """
+        return f"{cls._PREFIX}{content_id}" if content_id else content_id
+
+    @classmethod
+    def sans_prefix(cls, content_id: str) -> str:
+        """Remove the prefix from the given ID.
+
+        Args:
+            content_id: The ID to remove the prefix from.
+
+        Returns:
+            The ID with the prefix removed.
+        """
+        return (
+            content_id[len(cls._PREFIX) :]
+            if content_id.startswith(cls._PREFIX)
+            else content_id
+        )
+
+    def __init__(self, label: Text, content_id: str, disabled: bool = False) -> None:
         """Initialize a ContentTab.
 
         Args:
             label: The label to be displayed within the tab.
             content_id: The id of the content associated with the tab.
             disabled: Is the tab disabled?
         """
-        super().__init__(label, id=content_id, disabled=disabled)
+        super().__init__(label, id=self.add_prefix(content_id), disabled=disabled)
 
 
 class ContentTabs(Tabs):
@@ -53,9 +85,78 @@ def __init__(
             active: ID of the tab which should be active on start.
             tabbed_content: The associated TabbedContent instance.
         """
-        super().__init__(*tabs, active=active)
+        super().__init__(
+            *tabs, active=active if active is None else ContentTab.add_prefix(active)
+        )
         self.tabbed_content = tabbed_content
 
+    def get_content_tab(self, tab_id: str) -> ContentTab:
+        """Get the `ContentTab` associated with the given `TabPane` ID.
+
+        Args:
+            tab_id: The ID of the tab to get.
+
+        Returns:
+            The tab associated with that ID.
+        """
+        return self.query_one(f"#{ContentTab.add_prefix(tab_id)}", ContentTab)
+
+    def disable(self, tab_id: str) -> Tab:
+        """Disable the indicated tab.
+
+        Args:
+            tab_id: The ID of the [`Tab`][textual.widgets.Tab] to disable.
+
+        Returns:
+            The [`Tab`][textual.widgets.Tab] that was targeted.
+
+        Raises:
+            TabError: If there are any issues with the request.
+        """
+        return super().disable(ContentTab.add_prefix(tab_id))
+
+    def enable(self, tab_id: str) -> Tab:
+        """Enable the indicated tab.
+
+        Args:
+            tab_id: The ID of the [`Tab`][textual.widgets.Tab] to enable.
+
+        Returns:
+            The [`Tab`][textual.widgets.Tab] that was targeted.
+
+        Raises:
+            TabError: If there are any issues with the request.
+        """
+        return super().enable(ContentTab.add_prefix(tab_id))
+
+    def hide(self, tab_id: str) -> Tab:
+        """Hide the indicated tab.
+
+        Args:
+            tab_id: The ID of the [`Tab`][textual.widgets.Tab] to hide.
+
+        Returns:
+            The [`Tab`][textual.widgets.Tab] that was targeted.
+
+        Raises:
+            TabError: If there are any issues with the request.
+        """
+        return super().hide(ContentTab.add_prefix(tab_id))
+
+    def show(self, tab_id: str) -> Tab:
+        """Show the indicated tab.
+
+        Args:
+            tab_id: The ID of the [`Tab`][textual.widgets.Tab] to show.
+
+        Returns:
+            The [`Tab`][textual.widgets.Tab] that was targeted.
+
+        Raises:
+            TabError: If there are any issues with the request.
+        """
+        return super().show(ContentTab.add_prefix(tab_id))
+
 
 class TabPane(Widget):
     """A container for switchable content, with additional title.
@@ -142,10 +243,10 @@ class TabbedContent(Widget):
     class TabActivated(Message):
         """Posted when the active tab changes."""
 
-        ALLOW_SELECTOR_MATCH = {"tab"}
+        ALLOW_SELECTOR_MATCH = {"pane"}
         """Additional message attributes that can be used with the [`on` decorator][textual.on]."""
 
-        def __init__(self, tabbed_content: TabbedContent, tab: Tab) -> None:
+        def __init__(self, tabbed_content: TabbedContent, tab: ContentTab) -> None:
             """Initialize message.
 
             Args:
@@ -156,6 +257,8 @@ def __init__(self, tabbed_content: TabbedContent, tab: Tab) -> None:
             """The `TabbedContent` widget that contains the tab activated."""
             self.tab = tab
             """The `Tab` widget that was selected (contains the tab label)."""
+            self.pane = tabbed_content.get_pane(tab)
+            """The `TabPane` widget that was activated by selecting the tab."""
             super().__init__()
 
         @property
@@ -170,6 +273,7 @@ def control(self) -> TabbedContent:
         def __rich_repr__(self) -> Result:
             yield self.tabbed_content
             yield self.tab
+            yield self.pane
 
     class Cleared(Message):
         """Posted when there are no more tab panes."""
@@ -317,7 +421,11 @@ def add_pane(
         assert pane.id is not None
         pane.display = False
         return AwaitComplete(
-            tabs.add_tab(ContentTab(pane._title, pane.id), before=before, after=after),
+            tabs.add_tab(
+                ContentTab(pane._title, pane.id),
+                before=before if before is None else ContentTab.add_prefix(before),
+                after=after if after is None else ContentTab.add_prefix(after),
+            ),
             self.get_child_by_type(ContentSwitcher).mount(pane),
         )
 
@@ -331,7 +439,11 @@ def remove_pane(self, pane_id: str) -> AwaitComplete:
             An optionally awaitable object that waits for the pane to be removed
                 and the Cleared message to be posted.
         """
-        removal_awaitables = [self.get_child_by_type(ContentTabs).remove_tab(pane_id)]
+        removal_awaitables = [
+            self.get_child_by_type(ContentTabs).remove_tab(
+                ContentTab.add_prefix(pane_id)
+            )
+        ]
         try:
             removal_awaitables.append(
                 self.get_child_by_type(ContentSwitcher)
@@ -390,8 +502,8 @@ def _on_tabs_tab_activated(self, event: Tabs.TabActivated) -> None:
             # The message is relevant, so consume it and update state accordingly.
             event.stop()
             switcher = self.get_child_by_type(ContentSwitcher)
-            switcher.current = event.tab.id
-            self.active = event.tab.id
+            switcher.current = ContentTab.sans_prefix(event.tab.id)
+            self.active = ContentTab.sans_prefix(event.tab.id)
             self.post_message(
                 TabbedContent.TabActivated(
                     tabbed_content=self,
@@ -422,38 +534,77 @@ def _is_associated_tabs(self, tabs: Tabs) -> bool:
         """
         return isinstance(tabs, ContentTabs) and tabs.tabbed_content is self
 
-    def _watch_active(self, active: str) -> None:
+    def _watch_active(self, old_active: str, active: str) -> None:
         """Switch tabs when the active attributes changes."""
         with self.prevent(Tabs.TabActivated):
-            self.get_child_by_type(ContentTabs).active = active
+            self.get_child_by_type(ContentTabs).active = ContentTab.add_prefix(active)
             self.get_child_by_type(ContentSwitcher).current = active
 
     @property
     def tab_count(self) -> int:
         """Total number of tabs."""
         return self.get_child_by_type(ContentTabs).tab_count
 
+    def get_tab(self, pane_id: str | TabPane) -> Tab:
+        """Get the `Tab` associated with the given ID or `TabPane`.
+
+        Args:
+            pane_id: The ID of the pane, or the pane itself.
+
+        Returns:
+            The Tab associated with the ID.
+        """
+        if target_id := pane_id if isinstance(pane_id, str) else pane_id.id:
+            return self.get_child_by_type(ContentTabs).get_content_tab(target_id)
+        raise ValueError(
+            "'pane_id' must be a non-empty string or a TabPane with an id."
+        )
+
+    def get_pane(self, pane_id: str | ContentTab) -> TabPane:
+        """Get the `TabPane` associated with the given ID or tab.
+
+        Args:
+            pane_id: The ID of the pane to get, or the Tab it is associated with.
+
+        Returns:
+            The `TabPane` associated with the ID or the given tab.
+
+        Raises:
+            ValueError: Raised if no ID was available.
+        """
+        target_id: str | None = None
+        if isinstance(pane_id, ContentTab):
+            target_id = (
+                pane_id.id if pane_id.id is None else ContentTab.sans_prefix(pane_id.id)
+            )
+        else:
+            target_id = pane_id
+        if target_id:
+            pane = self.get_child_by_type(ContentSwitcher).get_child_by_id(target_id)
+            assert isinstance(pane, TabPane)
+            return pane
+        raise ValueError(
+            "'pane_id' must be a non-empty string or a ContentTab with an id."
+        )
+
     def _on_tabs_tab_disabled(self, event: Tabs.TabDisabled) -> None:
         """Disable the corresponding tab pane."""
         event.stop()
         tab_id = event.tab.id or ""
         try:
             with self.prevent(TabPane.Disabled):
                 self.get_child_by_type(ContentSwitcher).get_child_by_id(
-                    tab_id, expect_type=TabPane
+                    ContentTab.sans_prefix(tab_id), expect_type=TabPane
                 ).disabled = True
         except NoMatches:
             return
 
     def _on_tab_pane_disabled(self, event: TabPane.Disabled) -> None:
         """Disable the corresponding tab."""
         event.stop()
-        tab_pane_id = event.tab_pane.id or ""
         try:
             with self.prevent(Tab.Disabled):
-                self.get_child_by_type(ContentTabs).query_one(
-                    f"Tab#{tab_pane_id}"
-                ).disabled = True
+                self.get_tab(event.tab_pane).disabled = True
         except NoMatches:
             return
 
@@ -464,20 +615,17 @@ def _on_tabs_tab_enabled(self, event: Tabs.TabEnabled) -> None:
         try:
             with self.prevent(TabPane.Enabled):
                 self.get_child_by_type(ContentSwitcher).get_child_by_id(
-                    tab_id, expect_type=TabPane
+                    ContentTab.sans_prefix(tab_id), expect_type=TabPane
                 ).disabled = False
         except NoMatches:
             return
 
     def _on_tab_pane_enabled(self, event: TabPane.Enabled) -> None:
         """Enable the corresponding tab."""
         event.stop()
-        tab_pane_id = event.tab_pane.id or ""
         try:
-            with self.prevent(Tab.Enabled):
-                self.get_child_by_type(ContentTabs).query_one(
-                    f"Tab#{tab_pane_id}"
-                ).disabled = False
+            with self.prevent(Tab.Disabled):
+                self.get_tab(event.tab_pane).disabled = False
         except NoMatches:
             return
 

tests/snapshot_tests/snapshot_apps/modified_tabs.py

@@ -18,9 +18,9 @@ def compose(self) -> ComposeResult:
             yield Button()
 
     def on_mount(self) -> None:
-        self.query_one(TabbedContent).disable_tab(f"tab-1")
-        self.query_one(TabbedContent).disable_tab(f"tab-2")
-        self.query_one(TabbedContent).hide_tab(f"tab-3")
+        self.query_one(TabbedContent).disable_tab("tab-1")
+        self.query_one(TabbedContent).disable_tab("tab-2")
+        self.query_one(TabbedContent).hide_tab("tab-3")
 
 
 if __name__ == "__main__":