From 3245eb38bb5f6a4a95fbe282f30b88288c49505f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rodrigo=20Gir=C3=A3o=20Serr=C3=A3o?=
 <5621605+rodrigogiraoserrao@users.noreply.github.com>
Date: Tue, 9 May 2023 16:44:37 +0100
Subject: [PATCH] Make auto-focus a class var.

Related comments: https://github.com/Textualize/textual/pull/2527\#discussion_r1188776849
---
 src/textual/screen.py | 19 ++++++++++---------
 tests/test_screens.py |  8 ++++----
 2 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/src/textual/screen.py b/src/textual/screen.py
index 8bc9c0532..af0b006be 100644
--- a/src/textual/screen.py
+++ b/src/textual/screen.py
@@ -9,6 +9,7 @@ from typing import (
     TYPE_CHECKING,
     Awaitable,
     Callable,
+    ClassVar,
     Generic,
     Iterable,
     Iterator,
@@ -93,6 +94,13 @@ class ResultCallback(Generic[ScreenResultType]):
 class Screen(Generic[ScreenResultType], Widget):
     """The base class for screens."""
 
+    AUTO_FOCUS: ClassVar[str | None] = "*"
+    """A selector to determine what to focus automatically when the screen is activated.
+
+    The widget focused is the first that matches the given [CSS selector](/guide/queries/#query-selectors).
+    Set to `None` to disable auto focus.
+    """
+
     DEFAULT_CSS = """
     Screen {
         layout: vertical;
@@ -100,13 +108,6 @@ class Screen(Generic[ScreenResultType], Widget):
         background: $surface;
     }
     """
-
-    auto_focus: str | None = "*"
-    """A selector to determine what to focus automatically when the screen is activated.
-
-    The widget focused is the first that matches the given [CSS selector](/guide/queries/#query-selectors).
-    Set to `None` to disable auto focus.
-    """
     focused: Reactive[Widget | None] = Reactive(None)
     """The focused [widget][textual.widget.Widget] or `None` for no focus."""
     stack_updates: Reactive[int] = Reactive(0, repaint=False)
@@ -665,9 +666,9 @@ class Screen(Generic[ScreenResultType], Widget):
         """Screen has resumed."""
         self.stack_updates += 1
         size = self.app.size
-        if self.auto_focus is not None and self.focused is None:
+        if self.AUTO_FOCUS is not None and self.focused is None:
             try:
-                to_focus = self.query(self.auto_focus).first()
+                to_focus = self.query(self.AUTO_FOCUS).first()
             except NoMatches:
                 pass
             else:
diff --git a/tests/test_screens.py b/tests/test_screens.py
index 7e20348a9..2e3dbfcbe 100644
--- a/tests/test_screens.py
+++ b/tests/test_screens.py
@@ -170,24 +170,24 @@ async def test_auto_focus():
         assert isinstance(app.focused, Button)
         app.pop_screen()
 
-        MyScreen.auto_focus = None
+        MyScreen.AUTO_FOCUS = None
         await app.push_screen(MyScreen())
         assert app.focused is None
         app.pop_screen()
 
-        MyScreen.auto_focus = "Input"
+        MyScreen.AUTO_FOCUS = "Input"
         await app.push_screen(MyScreen())
         assert isinstance(app.focused, Input)
         assert app.focused.id == "one"
         app.pop_screen()
 
-        MyScreen.auto_focus = "#two"
+        MyScreen.AUTO_FOCUS = "#two"
         await app.push_screen(MyScreen())
         assert isinstance(app.focused, Input)
         assert app.focused.id == "two"
 
         # If we push and pop another screen, focus should be preserved for #two.
-        MyScreen.auto_focus = None
+        MyScreen.AUTO_FOCUS = None
         await app.push_screen(MyScreen())
         assert app.focused is None
         app.pop_screen()