Refactor WeakrefCallable to be a core handler

danyeaw · danyeaw · commit 52af22d27126 · 2025-03-07T16:46:48.000-05:00
diff --git a/core/src/toga/handlers.py b/core/src/toga/handlers.py
@@ -5,6 +5,7 @@
 import sys
 import traceback
 import warnings
+import weakref
 from abc import ABC
 from collections.abc import Awaitable, Callable, Generator
 from typing import TYPE_CHECKING, Any, NoReturn, Protocol, TypeVar, Union
@@ -259,3 +260,25 @@ def __bool__(self, other: object) -> NoReturn:
 
 class PermissionResult(AsyncResult):
     RESULT_TYPE = "permission"
+
+
+class WeakrefCallable:
+    """
+    A wrapper for callable that holds a weak reference to it.
+
+    This can be useful in particular when setting winforms event handlers, to avoid
+    cyclical reference cycles between Python and the .NET CLR that are detected neither
+    by the Python garbage collector nor the C# garbage collector. It is also used
+    for some of the GTK4 event controllers.
+    """
+
+    def __init__(self, function):
+        try:
+            self.ref = weakref.WeakMethod(function)
+        except TypeError:  # pragma: no cover
+            self.ref = weakref.ref(function)
+
+    def __call__(self, *args, **kwargs):
+        function = self.ref()
+        if function:  # pragma: no branch
+            return function(*args, **kwargs)
diff --git a/winforms/src/toga_winforms/app.py b/winforms/src/toga_winforms/app.py
@@ -10,8 +10,9 @@
 from System.Net import SecurityProtocolType, ServicePointManager
 from System.Windows.Threading import Dispatcher
 
+from toga.handlers import WeakrefCallable
+
 from .libs.proactor import WinformsProactorEventLoop
-from .libs.wrapper import WeakrefCallable
 from .screens import Screen as ScreenImpl
 
 
diff --git a/winforms/src/toga_winforms/dialogs.py b/winforms/src/toga_winforms/dialogs.py
@@ -9,8 +9,9 @@
 )
 from System.Windows.Forms import DialogResult, MessageBoxButtons, MessageBoxIcon
 
+from toga.handlers import WeakrefCallable
+
 from .libs.user32 import DPI_AWARENESS_CONTEXT_UNAWARE, SetThreadDpiAwarenessContext
-from .libs.wrapper import WeakrefCallable
 
 
 class BaseDialog:
diff --git a/winforms/src/toga_winforms/libs/wrapper.py b/winforms/src/toga_winforms/libs/wrapper.py
diff --git a/winforms/src/toga_winforms/statusicons.py b/winforms/src/toga_winforms/statusicons.py
@@ -2,8 +2,7 @@
 
 import toga
 from toga.command import Group, Separator
-
-from .libs.wrapper import WeakrefCallable
+from toga.handlers import WeakrefCallable
 
 
 class StatusIcon:
diff --git a/winforms/src/toga_winforms/widgets/button.py b/winforms/src/toga_winforms/widgets/button.py
@@ -4,8 +4,8 @@
 from travertino.size import at_least
 
 from toga.colors import TRANSPARENT
+from toga.handlers import WeakrefCallable
 
-from ..libs.wrapper import WeakrefCallable
 from .base import Widget
 
 
diff --git a/winforms/src/toga_winforms/widgets/canvas.py b/winforms/src/toga_winforms/widgets/canvas.py
@@ -24,10 +24,10 @@
 
 from toga.colors import TRANSPARENT
 from toga.constants import Baseline, FillRule
+from toga.handlers import WeakrefCallable
 from toga.widgets.canvas import arc_to_bezier, sweepangle
 from toga_winforms.colors import native_color
 
-from ..libs.wrapper import WeakrefCallable
 from .box import Box
 
 
diff --git a/winforms/src/toga_winforms/widgets/dateinput.py b/winforms/src/toga_winforms/widgets/dateinput.py
@@ -4,7 +4,8 @@
 import System.Windows.Forms as WinForms
 from System import DateTime as WinDateTime
 
-from ..libs.wrapper import WeakrefCallable
+from toga.handlers import WeakrefCallable
+
 from .base import Widget
 
 
diff --git a/winforms/src/toga_winforms/widgets/mapview.py b/winforms/src/toga_winforms/widgets/mapview.py
@@ -8,14 +8,14 @@
 from System.Threading.Tasks import Task, TaskScheduler
 
 import toga
+from toga.handlers import WeakrefCallable
 from toga.types import LatLng
 from toga_winforms.libs.extensions import (
     CoreWebView2CreationProperties,
     WebView2,
     WebView2RuntimeNotFoundException,
 )
 
-from ..libs.wrapper import WeakrefCallable
 from .base import Widget
 
 MAPVIEW_HTML_CONTENT = """<!DOCTYPE html>
diff --git a/winforms/src/toga_winforms/widgets/multilinetextinput.py b/winforms/src/toga_winforms/widgets/multilinetextinput.py
@@ -2,10 +2,10 @@
 from System.Drawing import SystemColors
 from travertino.size import at_least
 
+from toga.handlers import WeakrefCallable
 from toga_winforms.colors import native_color
 from toga_winforms.libs.fonts import HorizontalTextAlignment
 
-from ..libs.wrapper import WeakrefCallable
 from .textinput import TextInput
 
 
diff --git a/winforms/src/toga_winforms/widgets/numberinput.py b/winforms/src/toga_winforms/widgets/numberinput.py
@@ -4,10 +4,10 @@
 import System.Windows.Forms as WinForms
 from System import Convert, String
 
+from toga.handlers import WeakrefCallable
 from toga.widgets.numberinput import _clean_decimal
 from toga_winforms.libs.fonts import HorizontalTextAlignment
 
-from ..libs.wrapper import WeakrefCallable
 from .base import Widget
 
 
diff --git a/winforms/src/toga_winforms/widgets/optioncontainer.py b/winforms/src/toga_winforms/widgets/optioncontainer.py
@@ -1,7 +1,8 @@
 from System.Windows.Forms import TabControl, TabPage
 
+from toga.handlers import WeakrefCallable
+
 from ..container import Container
-from ..libs.wrapper import WeakrefCallable
 from .base import Widget
 
 
diff --git a/winforms/src/toga_winforms/widgets/scrollcontainer.py b/winforms/src/toga_winforms/widgets/scrollcontainer.py
@@ -4,9 +4,9 @@
 from System.Windows.Forms import Panel, SystemInformation
 from travertino.node import Node
 
+from toga.handlers import WeakrefCallable
 from toga_winforms.container import Container
 
-from ..libs.wrapper import WeakrefCallable
 from .base import Widget
 
 # On Windows, scroll bars usually appear only when the content is larger than the
diff --git a/winforms/src/toga_winforms/widgets/selection.py b/winforms/src/toga_winforms/widgets/selection.py
@@ -3,7 +3,8 @@
 
 import System.Windows.Forms as WinForms
 
-from ..libs.wrapper import WeakrefCallable
+from toga.handlers import WeakrefCallable
+
 from .base import Widget
 
 
diff --git a/winforms/src/toga_winforms/widgets/slider.py b/winforms/src/toga_winforms/widgets/slider.py
@@ -3,9 +3,9 @@
 import System.Windows.Forms as WinForms
 
 from toga.colors import TRANSPARENT
+from toga.handlers import WeakrefCallable
 from toga.widgets.slider import IntSliderImpl
 
-from ..libs.wrapper import WeakrefCallable
 from .base import Widget
 
 # Implementation notes
diff --git a/winforms/src/toga_winforms/widgets/splitcontainer.py b/winforms/src/toga_winforms/widgets/splitcontainer.py
@@ -5,9 +5,9 @@
 )
 
 from toga.constants import Direction
+from toga.handlers import WeakrefCallable
 
 from ..container import Container
-from ..libs.wrapper import WeakrefCallable
 from .base import Widget
 
 
diff --git a/winforms/src/toga_winforms/widgets/switch.py b/winforms/src/toga_winforms/widgets/switch.py
@@ -4,8 +4,8 @@
 from travertino.size import at_least
 
 from toga.colors import TRANSPARENT
+from toga.handlers import WeakrefCallable
 
-from ..libs.wrapper import WeakrefCallable
 from .base import Widget
 
 
diff --git a/winforms/src/toga_winforms/widgets/table.py b/winforms/src/toga_winforms/widgets/table.py
@@ -3,8 +3,8 @@
 import System.Windows.Forms as WinForms
 
 import toga
+from toga.handlers import WeakrefCallable
 
-from ..libs.wrapper import WeakrefCallable
 from .base import Widget
 
 
diff --git a/winforms/src/toga_winforms/widgets/textinput.py b/winforms/src/toga_winforms/widgets/textinput.py
@@ -4,10 +4,10 @@
 
 import System.Windows.Forms as WinForms
 
+from toga.handlers import WeakrefCallable
 from toga_winforms.colors import native_color
 from toga_winforms.libs.fonts import HorizontalTextAlignment
 
-from ..libs.wrapper import WeakrefCallable
 from .base import Widget
 
 
diff --git a/winforms/src/toga_winforms/widgets/timeinput.py b/winforms/src/toga_winforms/widgets/timeinput.py
@@ -4,7 +4,8 @@
 import System.Windows.Forms as WinForms
 from System import DateTime as WinDateTime
 
-from ..libs.wrapper import WeakrefCallable
+from toga.handlers import WeakrefCallable
+
 from .base import Widget
 
 
diff --git a/winforms/src/toga_winforms/widgets/webview.py b/winforms/src/toga_winforms/widgets/webview.py
@@ -13,6 +13,7 @@
 from System.Threading.Tasks import Task, TaskScheduler
 
 import toga
+from toga.handlers import WeakrefCallable
 from toga.widgets.webview import CookiesResult, JavaScriptResult
 from toga_winforms.libs.extensions import (
     CoreWebView2Cookie,
@@ -21,7 +22,6 @@
     WebView2RuntimeNotFoundException,
 )
 
-from ..libs.wrapper import WeakrefCallable
 from .base import Widget
 
 
diff --git a/winforms/src/toga_winforms/window.py b/winforms/src/toga_winforms/window.py
@@ -10,11 +10,11 @@
 from toga import App
 from toga.command import Separator
 from toga.constants import WindowState
+from toga.handlers import WeakrefCallable
 from toga.types import Position, Size
 
 from .container import Container
 from .fonts import DEFAULT_FONT
-from .libs.wrapper import WeakrefCallable
 from .screens import Screen as ScreenImpl
 from .widgets.base import Scalable
 

Original file line number	Diff line number	Diff line change
`@@ -9,8 +9,9 @@`
`9`	`9`	`)`
`10`	`10`	`from System.Windows.Forms import DialogResult, MessageBoxButtons, MessageBoxIcon`
`11`	`11`
	`12`	`+from toga.handlers import WeakrefCallable`
	`13`	`+`
`12`	`14`	`from .libs.user32 import DPI_AWARENESS_CONTEXT_UNAWARE, SetThreadDpiAwarenessContext`
`13`		`-from .libs.wrapper import WeakrefCallable`
`14`	`15`
`15`	`16`
`16`	`17`	`class BaseDialog:`
Original file line number	Diff line number	Diff line change
`@@ -5,9 +5,9 @@`
`5`	`5`	`)`
`6`	`6`
`7`	`7`	`from toga.constants import Direction`
	`8`	`+from toga.handlers import WeakrefCallable`
`8`	`9`
`9`	`10`	`from ..container import Container`
`10`		`-from ..libs.wrapper import WeakrefCallable`
`11`	`11`	`from .base import Widget`
`12`	`12`
`13`	`13`