From 23c57f0a3105f7c415c4b31032cd3f4f552dc77c Mon Sep 17 00:00:00 2001
From: Maic Siemering <maic@siemering.tech>
Date: Fri, 9 May 2025 23:25:20 +0200
Subject: [PATCH 1/9] remove some type ignores

---
 arcade/gui/widgets/__init__.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arcade/gui/widgets/__init__.py b/arcade/gui/widgets/__init__.py
index 244024cb37..ce551638c7 100644
--- a/arcade/gui/widgets/__init__.py
+++ b/arcade/gui/widgets/__init__.py
@@ -3,6 +3,7 @@
 from abc import ABC
 from collections.abc import Iterable
 from enum import IntEnum
+from types import EllipsisType
 from typing import TYPE_CHECKING, NamedTuple, TypeVar
 
 from pyglet.event import EVENT_HANDLED, EVENT_UNHANDLED, EventDispatcher
@@ -485,8 +486,8 @@ def with_padding(
     def with_background(
         self,
         *,
-        color: None | Color = ...,  # type: ignore
-        texture: None | Texture | NinePatchTexture = ...,  # type: ignore
+        color: Color | EllipsisType | None = ...,
+        texture: Texture | NinePatchTexture | EllipsisType | None = ...,
     ) -> Self:
         """Set widgets background.
 

From 4b1e9d42cee9e7c6ef3f3d7787903fd0075553e7 Mon Sep 17 00:00:00 2001
From: Maic Siemering <maic@siemering.tech>
Date: Sun, 11 May 2025 23:46:07 +0200
Subject: [PATCH 2/9] Allow property listener to receive: - no args - instance
 - instance, value - instance, value, old value

---
 arcade/gui/property.py          | 69 ++++++++++++++++++++++++++-------
 tests/unit/gui/test_property.py | 10 ++---
 2 files changed, 61 insertions(+), 18 deletions(-)

diff --git a/arcade/gui/property.py b/arcade/gui/property.py
index c9332c3ad4..c1fe26152b 100644
--- a/arcade/gui/property.py
+++ b/arcade/gui/property.py
@@ -1,6 +1,8 @@
+import inspect
 import sys
 import traceback
 from collections.abc import Callable
+from contextlib import suppress
 from typing import Any, Generic, TypeVar, cast
 from weakref import WeakKeyDictionary, ref
 
@@ -9,18 +11,64 @@
 P = TypeVar("P")
 
 
+NoArgListener = Callable[[], None]
+InstanceListener = Callable[[Any], None]
+InstanceValueListener = Callable[[Any, Any], None]
+InstanceNewOldListener = Callable[[Any, Any, Any], None]
+AnyListener = NoArgListener | InstanceListener | InstanceValueListener | InstanceNewOldListener
+
+
 class _Obs(Generic[P]):
     """
     Internal holder for Property value and change listeners
     """
 
-    __slots__ = ("value", "listeners")
+    __slots__ = ("value", "_listeners")
 
     def __init__(self, value: P):
         self.value = value
         # This will keep any added listener even if it is not referenced anymore
         # and would be garbage collected
-        self.listeners: set[Callable[[Any, P], Any] | Callable[[], Any]] = set()
+        self._listeners: dict[AnyListener, InstanceNewOldListener] = dict()
+
+    def add(
+        self,
+        callback: AnyListener,
+    ):
+        """Add a callback to the list of listeners"""
+        self._listeners[callback] = _Obs._normalize_callback(callback)
+
+    def remove(self, callback):
+        """Remove a callback from the list of listeners"""
+        if callback in self._listeners:
+            del self._listeners[callback]
+
+    @property
+    def listeners(self) -> list[InstanceNewOldListener]:
+        return list(self._listeners.values())
+
+    @staticmethod
+    def _normalize_callback(callback) -> InstanceNewOldListener:
+        """Normalizes the callback so every callback can be invoked with the same signature."""
+        signature = inspect.signature(callback)
+
+        with suppress(TypeError):
+            signature.bind(1, 1, 1)
+            return lambda instance, new, old: callback(instance, new, old)
+
+        with suppress(TypeError):
+            signature.bind(1, 1)
+            return lambda instance, new, old: callback(instance, new)
+
+        with suppress(TypeError):
+            signature.bind(1)
+            return lambda instance, new, old: callback(instance)
+
+        with suppress(TypeError):
+            signature.bind()
+            return lambda instance, new, old: callback()
+
+        raise TypeError("Callback is not callable")
 
 
 class Property(Generic[P]):
@@ -85,10 +133,11 @@ def set(self, instance, value):
         """Set value for owner instance"""
         obs = self._get_obs(instance)
         if obs.value != value:
+            old = obs.value
             obs.value = value
-            self.dispatch(instance, value)
+            self.dispatch(instance, value, old)
 
-    def dispatch(self, instance, value):
+    def dispatch(self, instance, value, old_value):
         """Notifies every listener, which subscribed to the change event.
 
         Args:
@@ -99,13 +148,7 @@ def dispatch(self, instance, value):
         obs = self._get_obs(instance)
         for listener in obs.listeners:
             try:
-                try:
-                    # FIXME if listener() raises an error, the invalid call will be
-                    #       also shown as an exception
-                    listener(instance, value)  # type: ignore
-                except TypeError:
-                    # If the listener does not accept arguments, we call it without it
-                    listener()  # type: ignore
+                listener(instance, value, old_value)
             except Exception:
                 print(
                     f"Change listener for {instance}.{self.name} = {value} raised an exception!",
@@ -126,7 +169,7 @@ def bind(self, instance, callback):
         # Instance methods are bound methods, which can not be referenced by normal `ref()`
         # if listeners would be a WeakSet, we would have to add listeners as WeakMethod
         # ourselves into `WeakSet.data`.
-        obs.listeners.add(callback)
+        obs.add(callback)
 
     def unbind(self, instance, callback):
         """Unbinds a function from the change event of the property.
@@ -136,7 +179,7 @@ def unbind(self, instance, callback):
             callback: The callback to unbind.
         """
         obs = self._get_obs(instance)
-        obs.listeners.remove(callback)
+        obs.remove(callback)
 
     def __set_name__(self, owner, name):
         self.name = name
diff --git a/tests/unit/gui/test_property.py b/tests/unit/gui/test_property.py
index 9ac5cefada..67d92c727b 100644
--- a/tests/unit/gui/test_property.py
+++ b/tests/unit/gui/test_property.py
@@ -70,7 +70,7 @@ def test_bind_callback_with_star_args():
     # WHEN
     my_obj.name = "New Name"
 
-    assert observer.call_args == (my_obj, "New Name")
+    assert observer.call_args == (my_obj, "New Name", None)
 
     # Remove reference of call_args to my_obj, otherwise it will keep the object alive
     observer.call_args = None
@@ -152,12 +152,12 @@ def test_gc_keeps_bound_methods():
 
     bind(obj, "name", observer.call)
 
-    assert len(MyObject.name.obs[obj].listeners) == 1
+    assert len(MyObject.name.obs[obj]._listeners) == 1
 
     del observer
     gc.collect()
 
-    assert len(MyObject.name.obs[obj].listeners) == 1
+    assert len(MyObject.name.obs[obj]._listeners) == 1
 
 
 def test_gc_keeps_temp_methods():
@@ -170,8 +170,8 @@ def callback(*args, **kwargs):
 
     bind(obj, "name", callback)
 
-    assert len(MyObject.name.obs[obj].listeners) == 1
+    assert len(MyObject.name.obs[obj]._listeners) == 1
 
     del callback
 
-    assert len(MyObject.name.obs[obj].listeners) == 1
+    assert len(MyObject.name.obs[obj]._listeners) == 1

From a1211eac1ebf55ae1dd66877809902dee91f1a74 Mon Sep 17 00:00:00 2001
From: Maic Siemering <maic@siemering.tech>
Date: Sun, 11 May 2025 23:48:15 +0200
Subject: [PATCH 3/9] Update change log

---
 CHANGELOG.md | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1759f78704..dd32999bb2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,13 @@ Arcade [PyPi Release History](https://pypi.org/project/arcade/#history) page.
 
 - Fixed an issue causing a crash when closing the window
 - Added `Window.close` (bool) attribute indicating if the window is closed
+- GUI
+  - Property listener can now receive:
+    - no args
+    - instance
+    - instance, value
+    - instance, value, old value
+    > This is a breaking change. If you are using the listener with *args.
 
 ## Version 3.2
 

From dc237226b6fa30aff2eebda460bbbf5f32d86445 Mon Sep 17 00:00:00 2001
From: Maic Siemering <maic@siemering.tech>
Date: Mon, 12 May 2025 00:08:49 +0200
Subject: [PATCH 4/9] Add tests for property callback

---
 tests/unit/gui/test_property.py | 81 +++++++++++++++++++++++++++++----
 1 file changed, 71 insertions(+), 10 deletions(-)

diff --git a/tests/unit/gui/test_property.py b/tests/unit/gui/test_property.py
index 67d92c727b..9f24401701 100644
--- a/tests/unit/gui/test_property.py
+++ b/tests/unit/gui/test_property.py
@@ -10,19 +10,35 @@ class MyObject:
 class Observer:
     call_args = None
     called = False
+    count = 0
 
     def call(self):
         self.call_args = tuple()
         self.called = True
+        self.count += 1
 
-    def call_with_args(self, instance, value):
+    def call_with_instance(self, instance):
+        """Match expected signature of 2 parameters"""
+        self.call_args = (instance,)
+        self.called = True
+        self.count += 1
+
+    def call_with_instance_value(self, instance, value):
         """Match expected signature of 2 parameters"""
         self.call_args = (instance, value)
         self.called = True
+        self.count += 1
 
-    def __call__(self, *args):
+    def call_with_instance_value_old(self, instance, value, old):
+        """Match expected signature of 2 parameters"""
+        self.call_args = (instance, value, old)
+        self.called = True
+        self.count += 1
+
+    def call_with_args(self, *args):
         self.call_args = args
         self.called = True
+        self.count += 1
 
 
 def test_bind_callback():
@@ -39,16 +55,44 @@ def test_bind_callback():
     assert observer.call_args == tuple()
 
 
-def test_bind_callback_with_args():
-    """
-    A bound callback can have 0 or 2 arguments.
-    0 arguments are used for simple callbacks, like `log_change`.
-    2 arguments are used for callbacks that need to know the instance and the new value.
-    """
+def test_bind_callback_only_once():
     observer = Observer()
 
     my_obj = MyObject()
-    bind(my_obj, "name", observer.call_with_args)
+    bind(my_obj, "name", observer.call)
+    bind(my_obj, "name", observer.call)
+
+    assert not observer.call_args
+
+    # WHEN
+    my_obj.name = "New Name"
+
+    assert observer.call_args == tuple()
+    assert observer.count == 1
+
+
+def test_bind_callback_accepts_instance():
+    observer = Observer()
+
+    my_obj = MyObject()
+    bind(my_obj, "name", observer.call_with_instance)
+
+    assert not observer.call_args
+
+    # WHEN
+    my_obj.name = "New Name"
+
+    assert observer.call_args == (my_obj,)
+
+    # Remove reference of call_args to my_obj, otherwise it will keep the object alive
+    observer.call_args = None
+
+
+def test_bind_callback_accepts_instance_value():
+    observer = Observer()
+
+    my_obj = MyObject()
+    bind(my_obj, "name", observer.call_with_instance_value)
 
     assert not observer.call_args
 
@@ -61,11 +105,28 @@ def test_bind_callback_with_args():
     observer.call_args = None
 
 
+def test_bind_callback_accepts_instance_value_old():
+    observer = Observer()
+
+    my_obj = MyObject()
+    bind(my_obj, "name", observer.call_with_instance_value_old)
+
+    assert not observer.call_args
+
+    # WHEN
+    my_obj.name = "New Name"
+
+    assert observer.call_args == (my_obj, "New Name", None)
+
+    # Remove reference of call_args to my_obj, otherwise it will keep the object alive
+    observer.call_args = None
+
+
 def test_bind_callback_with_star_args():
     observer = Observer()
 
     my_obj = MyObject()
-    bind(my_obj, "name", observer)
+    bind(my_obj, "name", observer.call_with_args)
 
     # WHEN
     my_obj.name = "New Name"

From d5cc38483dd1b208a7d8d77ae1f948707af00c76 Mon Sep 17 00:00:00 2001
From: Maic Siemering <maic@siemering.tech>
Date: Mon, 12 May 2025 00:20:54 +0200
Subject: [PATCH 5/9] Make DictProperty and ListProperty also dispatch old
 state

---
 arcade/gui/property.py          | 105 ++++++++++++++++++--------------
 tests/unit/gui/test_property.py |   5 ++
 2 files changed, 63 insertions(+), 47 deletions(-)

diff --git a/arcade/gui/property.py b/arcade/gui/property.py
index c1fe26152b..0c19f3c80c 100644
--- a/arcade/gui/property.py
+++ b/arcade/gui/property.py
@@ -2,7 +2,7 @@
 import sys
 import traceback
 from collections.abc import Callable
-from contextlib import suppress
+from contextlib import suppress, contextmanager
 from typing import Any, Generic, TypeVar, cast
 from weakref import WeakKeyDictionary, ref
 
@@ -142,7 +142,8 @@ def dispatch(self, instance, value, old_value):
 
         Args:
             instance: Property instance
-            value: new value to set
+            value: new value set
+            old_value: previous value
 
         """
         obs = self._get_obs(instance)
@@ -275,45 +276,49 @@ def __init__(self, prop: Property, instance, *args):
         self.obj = ref(instance)
         super().__init__(*args)
 
-    def dispatch(self):
-        self.prop.dispatch(self.obj(), self)
+    @contextmanager
+    def _dispatch(self):
+        """This is a context manager which will dispatch the change event
+        when the context is exited.
+        """
+        old_value = self.copy()
+        yield
+        self.prop.dispatch(self.obj(), self, old_value)
 
     @override
     def __setitem__(self, key, value):
-        dict.__setitem__(self, key, value)
-        self.dispatch()
+        with self._dispatch():
+            dict.__setitem__(self, key, value)
 
     @override
     def __delitem__(self, key):
-        dict.__delitem__(self, key)
-        self.dispatch()
+        with self._dispatch():
+            dict.__delitem__(self, key)
 
     @override
     def clear(self):
-        dict.clear(self)
-        self.dispatch()
+        with self._dispatch():
+            dict.clear(self)
 
     @override
     def pop(self, *args):
-        result = dict.pop(self, *args)
-        self.dispatch()
-        return result
+        with self._dispatch():
+            return dict.pop(self, *args)
 
     @override
     def popitem(self):
-        result = dict.popitem(self)
-        self.dispatch()
-        return result
+        with self._dispatch():
+            return dict.popitem(self)
 
     @override
     def setdefault(self, *args):
-        dict.setdefault(self, *args)
-        self.dispatch()
+        with self._dispatch():
+            return dict.setdefault(self, *args)
 
     @override
     def update(self, *args):
-        dict.update(self, *args)
-        self.dispatch()
+        with self._dispatch():
+            dict.update(self, *args)
 
 
 K = TypeVar("K")
@@ -352,80 +357,86 @@ def __init__(self, prop: Property, instance, *args):
         self.obj = ref(instance)
         super().__init__(*args)
 
-    def dispatch(self):
-        """Dispatches the change event."""
-        self.prop.dispatch(self.obj(), self)
+    @contextmanager
+    def _dispatch(self):
+        """Dispatches the change event.
+        This is a context manager which will dispatch the change event
+        when the context is exited.
+        """
+        old_value = self.copy()
+        yield
+        self.prop.dispatch(self.obj(), self, old_value)
 
     @override
     def __setitem__(self, key, value):
-        list.__setitem__(self, key, value)
-        self.dispatch()
+        with self._dispatch():
+            list.__setitem__(self, key, value)
 
     @override
     def __delitem__(self, key):
-        list.__delitem__(self, key)
-        self.dispatch()
+        with self._dispatch():
+            list.__delitem__(self, key)
 
     @override
     def __iadd__(self, *args):
-        list.__iadd__(self, *args)
-        self.dispatch()
+        with self._dispatch():
+            list.__iadd__(self, *args)
         return self
 
     @override
     def __imul__(self, *args):
-        list.__imul__(self, *args)
-        self.dispatch()
+        with self._dispatch():
+            list.__imul__(self, *args)
         return self
 
     @override
     def append(self, *args):
         """Proxy for list.append() which dispatches the change event."""
-        list.append(self, *args)
-        self.dispatch()
+        with self._dispatch():
+            list.append(self, *args)
 
     @override
     def clear(self):
         """Proxy for list.clear() which dispatches the change event."""
-        list.clear(self)
-        self.dispatch()
+        with self._dispatch():
+            list.clear(self)
 
     @override
     def remove(self, *args):
         """Proxy for list.remove() which dispatches the change event."""
-        list.remove(self, *args)
-        self.dispatch()
+        with self._dispatch():
+            list.remove(self, *args)
 
     @override
     def insert(self, *args):
         """Proxy for list.insert() which dispatches the change event."""
-        list.insert(self, *args)
-        self.dispatch()
+        with self._dispatch():
+            list.insert(self, *args)
 
     @override
     def pop(self, *args):
         """Proxy for list.pop() which dispatches the change"""
-        result = list.pop(self, *args)
-        self.dispatch()
+        with self._dispatch():
+            result = list.pop(self, *args)
         return result
 
     @override
     def extend(self, *args):
         """Proxy for list.extend() which dispatches the change event."""
-        list.extend(self, *args)
-        self.dispatch()
+        with self._dispatch():
+            list.extend(self, *args)
 
     @override
     def sort(self, **kwargs):
         """Proxy for list.sort() which dispatches the change event."""
-        list.sort(self, **kwargs)
-        self.dispatch()
+        with self._dispatch():
+            list.sort(self, **kwargs)
 
     @override
     def reverse(self):
         """Proxy for list.reverse() which dispatches the change event."""
-        list.reverse(self)
-        self.dispatch()
+        with self._dispatch():
+            list.reverse(self)
 
 
 class ListProperty(Property[list[P]], Generic[P]):
diff --git a/tests/unit/gui/test_property.py b/tests/unit/gui/test_property.py
index 9f24401701..64a11047e7 100644
--- a/tests/unit/gui/test_property.py
+++ b/tests/unit/gui/test_property.py
@@ -40,6 +40,11 @@ def call_with_args(self, *args):
         self.called = True
         self.count += 1
 
+    def __call__(self, *args, **kwargs):
+        self.call_args = args
+        self.called = True
+        self.count += 1
+
 
 def test_bind_callback():
     observer = Observer()

From 101352b6434c0a378132076c379c8cbe2180fd17 Mon Sep 17 00:00:00 2001
From: Maic Siemering <maic@siemering.tech>
Date: Fri, 16 May 2025 16:00:35 +0100
Subject: [PATCH 6/9] Make property changes backwards compatible also for *args

---
 CHANGELOG.md                    | 2 +-
 arcade/gui/property.py          | 8 ++++----
 tests/unit/gui/test_property.py | 2 +-
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index dd32999bb2..8bf273c8c3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,7 +13,7 @@ Arcade [PyPi Release History](https://pypi.org/project/arcade/#history) page.
     - instance
     - instance, value
     - instance, value, old value
-    > This is a breaking change. If you are using the listener with *args.
+    > Listener accepting `*args` receive `instance, value` like in previous versions.
 
 ## Version 3.2
 
diff --git a/arcade/gui/property.py b/arcade/gui/property.py
index 0c19f3c80c..b96710ac46 100644
--- a/arcade/gui/property.py
+++ b/arcade/gui/property.py
@@ -52,14 +52,14 @@ def _normalize_callback(callback) -> InstanceNewOldListener:
         """Normalizes the callback so every callback can be invoked with the same signature."""
         signature = inspect.signature(callback)
 
-        with suppress(TypeError):
-            signature.bind(1, 1, 1)
-            return lambda instance, new, old: callback(instance, new, old)
-
         with suppress(TypeError):
             signature.bind(1, 1)
             return lambda instance, new, old: callback(instance, new)
 
+        with suppress(TypeError):
+            signature.bind(1, 1, 1)
+            return lambda instance, new, old: callback(instance, new, old)
+
         with suppress(TypeError):
             signature.bind(1)
             return lambda instance, new, old: callback(instance)
diff --git a/tests/unit/gui/test_property.py b/tests/unit/gui/test_property.py
index 64a11047e7..9c783e06a1 100644
--- a/tests/unit/gui/test_property.py
+++ b/tests/unit/gui/test_property.py
@@ -136,7 +136,7 @@ def test_bind_callback_with_star_args():
     # WHEN
     my_obj.name = "New Name"
 
-    assert observer.call_args == (my_obj, "New Name", None)
+    assert observer.call_args == (my_obj, "New Name")
 
     # Remove reference of call_args to my_obj, otherwise it will keep the object alive
     observer.call_args = None

From 60df022ec45466ace03dc4af99f5bc067ef85e18 Mon Sep 17 00:00:00 2001
From: Maic Siemering <maic@siemering.tech>
Date: Fri, 16 May 2025 18:09:43 +0100
Subject: [PATCH 7/9] Fix some typing

---
 arcade/types/rect.py | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/arcade/types/rect.py b/arcade/types/rect.py
index cac1acab1b..3e2db6d25a 100644
--- a/arcade/types/rect.py
+++ b/arcade/types/rect.py
@@ -717,16 +717,16 @@ def kwargs(self) -> RectKwargs:
            checking. See :py:class:`typing.TypedDict` to learn more.
 
         """
-        return {
-            "left": self.left,
-            "right": self.right,
-            "bottom": self.bottom,
-            "top": self.top,
-            "x": self.x,
-            "y": self.y,
-            "width": self.width,
-            "height": self.height,
-        }
+        return RectKwargs(
+            left=self.left,
+            right=self.right,
+            bottom=self.bottom,
+            top=self.top,
+            x=self.x,
+            y=self.y,
+            width=self.width,
+            height=self.height,
+        )
 
     # Since __repr__ is handled automatically by NamedTuple, we focus on
     # human-readable spot-check values for __str__ instead.

From ca8492f3ff18e503ea1fe0620e0018a46950ebf0 Mon Sep 17 00:00:00 2001
From: Maic Siemering <maic@siemering.tech>
Date: Mon, 16 Jun 2025 20:24:10 +0200
Subject: [PATCH 8/9] remove todo, which does not improve code

---
 arcade/gui/widgets/slider.py | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arcade/gui/widgets/slider.py b/arcade/gui/widgets/slider.py
index b17847acd0..12e632b648 100644
--- a/arcade/gui/widgets/slider.py
+++ b/arcade/gui/widgets/slider.py
@@ -115,8 +115,6 @@ def _apply_step(self, value: float):
         return value
 
     def _set_value(self, value: float):
-        # TODO changing the value itself should trigger `on_change` event
-        # current problem is, that the property does not pass the old value to listeners
         if value < self.min_value:
             value = self.min_value
         elif value > self.max_value:

From 63151819d5a2dbdd6067ce45f13c9e8c2cd0225b Mon Sep 17 00:00:00 2001
From: Maic Siemering <maic@siemering.tech>
Date: Mon, 16 Jun 2025 20:32:43 +0200
Subject: [PATCH 9/9] sort import

---
 arcade/gui/property.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arcade/gui/property.py b/arcade/gui/property.py
index b96710ac46..2bcd5496fc 100644
--- a/arcade/gui/property.py
+++ b/arcade/gui/property.py
@@ -2,7 +2,7 @@
 import sys
 import traceback
 from collections.abc import Callable
-from contextlib import suppress, contextmanager
+from contextlib import contextmanager, suppress
 from typing import Any, Generic, TypeVar, cast
 from weakref import WeakKeyDictionary, ref