implements screens view

CHANGELOG.md

@@ -19,13 +19,20 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Added Shift+scroll wheel and ctrl+scroll wheel to scroll horizontally
 - Added `Tree.action_toggle_node` to toggle a node without selecting, and bound it to <kbd>Space</kbd> https://github.com/Textualize/textual/issues/1433
 - Added `Tree.reset` to fully reset a `Tree` https://github.com/Textualize/textual/issues/1437
-- Added DOMNode.watch and DOMNode.is_attached methods  https://github.com/Textualize/textual/pull/1750
+- Added `DOMNode.watch` and `DOMNode.is_attached` methods  https://github.com/Textualize/textual/pull/1750
+- Added `DOMNode.css_tree` which is a renderable that shows the DOM and CSS https://github.com/Textualize/textual/pull/1778
+- Added `DOMNode.children_view` which is a view on to a nodes children list, use for querying https://github.com/Textualize/textual/pull/1778
 
 ### Changed
 
 - Breaking change: `TreeNode` can no longer be imported from `textual.widgets`; it is now available via `from textual.widgets.tree import TreeNode`. https://github.com/Textualize/textual/pull/1637
 - `Tree` now shows a (subdued) cursor for a highlighted node when focus has moved elsewhere https://github.com/Textualize/textual/issues/1471
 - Breaking change: renamed `Checkbox` to `Switch` https://github.com/Textualize/textual/issues/1746
+- `App.install_screen` name is no longer optional https://github.com/Textualize/textual/pull/1778
+- `App.query` now only includes the current screen https://github.com/Textualize/textual/pull/1778
+- `DOMNode.tree` now displays simple DOM structure only https://github.com/Textualize/textual/pull/1778
+- `App.install_screen` now returns None rather than AwaitMount https://github.com/Textualize/textual/pull/1778
+- `DOMNode.children` is now a simple sequence, the NodesList is exposed as `DOMNode._nodes` https://github.com/Textualize/textual/pull/1778
 
 ### Fixed
 

docs/widgets/tree.md

@@ -21,7 +21,7 @@ The example below creates a simple tree.
     --8<-- "docs/examples/widgets/tree.py"
     ```
 
-Tree widgets have a "root" attribute which is an instance of a [TreeNode][textual.widgets.tree.TreeNode]. Call [add()][textual.widgets.tree.TreeNode.add] or [add_leaf()][textual.widgets.tree,TreeNode.add_leaf] to add new nodes underneath the root. Both these methods return a TreeNode for the child which you can use to add additional levels.
+Tree widgets have a "root" attribute which is an instance of a [TreeNode][textual.widgets.tree.TreeNode]. Call [add()][textual.widgets.tree.TreeNode.add] or [add_leaf()][textual.widgets.tree.TreeNode.add_leaf] to add new nodes underneath the root. Both these methods return a TreeNode for the child which you can use to add additional levels.
 
 
 ## Reactive Attributes

pyproject.toml

@@ -47,7 +47,6 @@ typing-extensions = "^4.0.0"
 aiohttp = { version = ">=3.8.1", optional = true }
 click = {version = ">=8.1.2", optional = true}
 msgpack = { version = ">=1.0.3", optional = true }
-nanoid = ">=2.0.0"
 mkdocs-exclude = "^1.0.2"
 
 [tool.poetry.extras]

src/textual/_layout.py

@@ -57,7 +57,7 @@ def get_content_width(self, widget: Widget, container: Size, viewport: Size) ->
         Returns:
             Width of the content.
         """
-        if not widget.children:
+        if not widget._nodes:
             width = 0
         else:
             # Use a size of 0, 0 to ignore relative sizes, since those are flexible anyway
@@ -85,7 +85,7 @@ def get_content_height(
         Returns:
             Content height (in lines).
         """
-        if not widget.children:
+        if not widget._nodes:
             height = 0
         else:
             # Use a height of zero to ignore relative heights

src/textual/app.py

@@ -25,15 +25,15 @@
     Generic,
     Iterable,
     List,
+    Sequence,
     Type,
     TypeVar,
     Union,
     cast,
     overload,
 )
-from weakref import WeakSet, WeakValueDictionary
+from weakref import WeakSet
 
-import nanoid
 import rich
 import rich.repr
 from rich.console import Console, RenderableType
@@ -385,9 +385,7 @@ def __init__(
         self.scroll_sensitivity_y: float = 2.0
         """Number of lines to scroll in the Y direction with wheel or trackpad."""
 
-        self._installed_screens: WeakValueDictionary[
-            str, Screen | Callable[[], Screen]
-        ] = WeakValueDictionary()
+        self._installed_screens: dict[str, Screen | Callable[[], Screen]] = {}
         self._installed_screens.update(**self.SCREENS)
 
         self.devtools: DevtoolsClient | None = None
@@ -420,6 +418,14 @@ def return_value(self) -> ReturnType | None:
         """ReturnType | None: The return type of the app."""
         return self._return_value
 
+    @property
+    def children(self) -> Sequence["Widget"]:
+        """A view on to the children which contains just the screen."""
+        try:
+            return (self.screen,)
+        except ScreenError:
+            return ()
+
     def animate(
         self,
         attribute: str,
@@ -1265,38 +1271,41 @@ def switch_screen(self, screen: Screen | str) -> AwaitMount:
             return await_mount
         return AwaitMount(self.screen, [])
 
-    def install_screen(self, screen: Screen, name: str | None = None) -> AwaitMount:
+    def install_screen(self, screen: Screen, name: str) -> None:
         """Install a screen.
 
         Installing a screen prevents Textual from destroying it when it is no longer on the screen stack.
+        Note that you don't need to install a screen to use it. See [push_screen][textual.app.App.push_screen]
+        or [switch_screen][textual.app.App.switch_screen] to make a new screen current.
 
         Args:
             screen: Screen to install.
-            name: Unique name of screen or None to auto-generate.
-                Defaults to None.
+            name: Unique name to identify the screen.
 
         Raises:
             ScreenError: If the screen can't be installed.
 
         Returns:
             An awaitable that awaits the mounting of the screen and its children.
         """
-        if name is None:
-            name = nanoid.generate()
         if name in self._installed_screens:
             raise ScreenError(f"Can't install screen; {name!r} is already installed")
         if screen in self._installed_screens.values():
             raise ScreenError(
                 "Can't install screen; {screen!r} has already been installed"
             )
         self._installed_screens[name] = screen
-        _screen, await_mount = self._get_screen(name)  # Ensures screen is running
         self.log.system(f"{screen} INSTALLED name={name!r}")
-        return await_mount
 
     def uninstall_screen(self, screen: Screen | str) -> str | None:
-        """Uninstall a screen. If the screen was not previously installed then this
-        method is a null-op.
+        """Uninstall a screen.
+
+        If the screen was not previously installed then this method is a null-op.
+        Uninstalling a screen allows Textual to delete it when it is popped or switched.
+        Note that uninstalling a screen is only required if you have previously installed it
+        with [install_screen][textual.app.App.install_screen].
+        Textual will also uninstall screens automatically on exit.
+
 
         Args:
             screen: The screen to uninstall or the name of a installed screen.
@@ -1641,19 +1650,19 @@ def _register_child(
             # Now to figure out where to place it. If we've got a `before`...
             if before is not None:
                 # ...it's safe to NodeList._insert before that location.
-                parent.children._insert(before, child)
+                parent._nodes._insert(before, child)
             elif after is not None and after != -1:
                 # In this case we've got an after. -1 holds the special
                 # position (for now) of meaning "okay really what I mean is
                 # do an append, like if I'd asked to add with no before or
                 # after". So... we insert before the next item in the node
                 # list, iff after isn't -1.
-                parent.children._insert(after + 1, child)
+                parent._nodes._insert(after + 1, child)
             else:
                 # At this point we appear to not be adding before or after,
                 # or we've got a before/after value that really means
                 # "please append". So...
-                parent.children._append(child)
+                parent._nodes._append(child)
 
             # Now that the widget is in the NodeList of its parent, sort out
             # the rest of the admin.
@@ -1698,8 +1707,8 @@ def _register(
                 raise AppError(f"Can't register {widget!r}; expected a Widget instance")
             if widget not in self._registry:
                 self._register_child(parent, widget, before, after)
-                if widget.children:
-                    self._register(widget, *widget.children)
+                if widget._nodes:
+                    self._register(widget, *widget._nodes)
                 apply_stylesheet(widget)
 
         if not self._running:
@@ -1716,7 +1725,7 @@ def _unregister(self, widget: Widget) -> None:
         """
         widget.reset_focus()
         if isinstance(widget._parent, Widget):
-            widget._parent.children._remove(widget)
+            widget._parent._nodes._remove(widget)
             widget._detach()
         self._registry.discard(widget)
 
@@ -1894,6 +1903,7 @@ async def on_event(self, event: events.Event) -> None:
         # Handle input events that haven't been forwarded
         # If the event has been forwarded it may have bubbled up back to the App
         if isinstance(event, events.Compose):
+            self.log(event)
             screen = Screen(id="_default")
             self._register(self, screen)
             self._screen_stack.append(screen)
@@ -2098,7 +2108,7 @@ def _detach_from_dom(self, widgets: list[Widget]) -> list[Widget]:
         # snipping each affected branch from the DOM.
         for widget in pruned_remove:
             if widget.parent is not None:
-                widget.parent.children._remove(widget)
+                widget.parent._nodes._remove(widget)
 
         # Return the list of widgets that should end up being sent off in a
         # prune event.
@@ -2117,10 +2127,10 @@ def _walk_children(self, root: Widget) -> Iterable[list[Widget]]:
 
         while stack:
             widget = pop()
-            children = [*widget.children, *widget._get_virtual_dom()]
+            children = [*widget._nodes, *widget._get_virtual_dom()]
             if children:
                 yield children
-            for child in widget.children:
+            for child in widget._nodes:
                 push(child)
 
     def _remove_nodes(self, widgets: list[Widget]) -> AwaitRemove:

src/textual/dom.py

@@ -7,6 +7,7 @@
     ClassVar,
     Iterable,
     Iterator,
+    Sequence,
     Type,
     TypeVar,
     cast,
@@ -132,7 +133,7 @@ def __init__(
         check_identifiers("class name", *_classes)
         self._classes.update(_classes)
 
-        self.children: NodeList = NodeList()
+        self._nodes: NodeList = NodeList()
         self._css_styles: Styles = Styles(self)
         self._inline_styles: Styles = Styles(self)
         self.styles: RenderStyles = RenderStyles(
@@ -150,6 +151,11 @@ def __init__(
 
         super().__init__()
 
+    @property
+    def children(self) -> Sequence["Widget"]:
+        """A view on to the children."""
+        return self._nodes
+
     @property
     def auto_refresh(self) -> float | None:
         return self._auto_refresh
@@ -484,7 +490,7 @@ def visible(self) -> bool:
         return self.styles.visibility != "hidden"
 
     @visible.setter
-    def visible(self, new_value: bool) -> None:
+    def visible(self, new_value: bool | str) -> None:
         if isinstance(new_value, bool):
             self.styles.visibility = "visible" if new_value else "hidden"
         elif new_value in VALID_VISIBILITY:
@@ -497,10 +503,27 @@ def visible(self, new_value: bool) -> None:
 
     @property
     def tree(self) -> Tree:
-        """Get a Rich tree object which will recursively render the structure of the node tree.
+        """Get a Rich tree object which will recursively render the structure of the node tree."""
 
-        Returns:
-            A Rich object which may be printed.
+        def render_info(node: DOMNode) -> Pretty:
+            return Pretty(node)
+
+        tree = Tree(render_info(self))
+
+        def add_children(tree, node):
+            for child in node.children:
+                info = render_info(child)
+                branch = tree.add(info)
+                if tree.children:
+                    add_children(branch, child)
+
+        add_children(tree, self)
+        return tree
+
+    @property
+    def css_tree(self) -> Tree:
+        """Get a Rich tree object which will recursively render the structure of the node tree,
+        which also displays CSS and size information.
         """
         from rich.columns import Columns
         from rich.console import Group
@@ -648,7 +671,7 @@ def displayed_children(self) -> list[Widget]:
             Children of this widget which will be displayed.
 
         """
-        return [child for child in self.children if child.display]
+        return [child for child in self._nodes if child.display]
 
     def watch(
         self,
@@ -691,7 +714,7 @@ def _add_child(self, node: Widget) -> None:
         Args:
             node: A DOM node.
         """
-        self.children._append(node)
+        self._nodes._append(node)
         node._attach(self)
 
     def _add_children(self, *nodes: Widget) -> None:
@@ -700,7 +723,7 @@ def _add_children(self, *nodes: Widget) -> None:
         Args:
             *nodes: Positional args should be new DOM nodes.
         """
-        _append = self.children._append
+        _append = self._nodes._append
         for node in nodes:
             node._attach(self)
             _append(node)

src/textual/drivers/linux_driver.py

@@ -236,5 +236,4 @@ def more_data() -> bool:
         except Exception as error:
             log(error)
         finally:
-            with timer("selector.close"):
-                selector.close()
+            selector.close()

src/textual/walk.py

@@ -53,7 +53,7 @@ def walk_depth_first(
     """
     from textual.dom import DOMNode
 
-    stack: list[Iterator[DOMNode]] = [iter(root.children)]
+    stack: list[Iterator[DOMNode]] = [iter(root._nodes)]
     pop = stack.pop
     push = stack.append
     check_type = filter_type or DOMNode