Add exception-raising copy dunders via reusable decorator (#2076)

* Add exception-raising BasicSprite copy dunders

* Add tests + correct deepcopy dunder issue

* Replace BasicSprite's copy dunders with reusable decorator

* Add copy dunder decorator stub to SpriteList

* Apply decorator to SpriteList

* Add tests for SpriteList

* Add copy dunder warning + tests for Shapes & ShapeElementList

* Apply copy dunder decorator to basic physics engines

* Remove Self from decorator helper

* Add tests for simpler physics engine no-copy decoration

* Add copy decorator + test for PyMunkPhysicsEngine

* Add copy dunder decorator to UIWidget

* Add TypeVar to decorator to preserve type info

Author: pushfoo

arcade/gui/widgets/__init__.py

@@ -34,6 +34,7 @@
 from arcade.gui.property import Property, bind, ListProperty
 from arcade.gui.surface import Surface
 from arcade.types import RGBA255, Color, Point, AsFloat
+from arcade.utils import copy_dunders_unimplemented
 
 if TYPE_CHECKING:
     from arcade.gui.ui_manager import UIManager
@@ -263,6 +264,7 @@ class _ChildEntry(NamedTuple):
     data: Dict
 
 
+@copy_dunders_unimplemented
 class UIWidget(EventDispatcher, ABC):
     """
     The :class:`UIWidget` class is the base class required for creating widgets.

arcade/physics_engines.py

@@ -21,6 +21,8 @@
     "PhysicsEnginePlatformer"
 ]
 
+from arcade.utils import copy_dunders_unimplemented
+
 
 def _circular_check(player: Sprite, walls: List[SpriteList]):
     """
@@ -221,6 +223,7 @@ def _move_sprite(moving_sprite: Sprite, walls: List[SpriteList[SpriteType]], ram
     return complete_hit_list
 
 
+@copy_dunders_unimplemented
 class PhysicsEngineSimple:
     """
     Simplistic physics engine for use in games without gravity, such as top-down
@@ -266,6 +269,7 @@ def update(self):
         return _move_sprite(self.player_sprite, self.walls, ramp_up=False)
 
 
+@copy_dunders_unimplemented
 class PhysicsEnginePlatformer:
     """
     Simplistic physics engine for use in a platformer. It is easier to get

arcade/pymunk_physics_engine.py

@@ -18,6 +18,7 @@
     "PymunkPhysicsEngine"
 ]
 
+from arcade.utils import copy_dunders_unimplemented
 
 LOG = logging.getLogger(__name__)
 
@@ -36,6 +37,8 @@ class PymunkException(Exception):
     pass
 
 
+# Temp fix for https://github.com/pythonarcade/arcade/issues/2074
+@copy_dunders_unimplemented
 class PymunkPhysicsEngine:
     """
     Pymunk Physics Engine

arcade/shape_list.py

@@ -26,6 +26,8 @@
 import pyglet.gl as gl
 
 from arcade.types import Color, Point, PointList, RGBA255
+
+from arcade.utils import copy_dunders_unimplemented
 from arcade import get_window, get_points_for_thick_line
 from arcade.gl import BufferDescription
 from arcade.gl import Program
@@ -59,6 +61,7 @@
 ]
 
 
+@copy_dunders_unimplemented  # Temp fix for https://github.com/pythonarcade/arcade/issues/2074
 class Shape:
     """
     A container for arbitrary geometry representing a shape.
@@ -747,6 +750,7 @@ def create_ellipse_filled_with_colors(
 TShape = TypeVar('TShape', bound=Shape)
 
 
+@copy_dunders_unimplemented
 class ShapeElementList(Generic[TShape]):
     """
     A ShapeElementList is a list of shapes that can be drawn together

arcade/sprite/base.py

@@ -7,6 +7,7 @@
 from arcade.color import BLACK, WHITE
 from arcade.hitbox import HitBox
 from arcade.texture import Texture
+from arcade.utils import copy_dunders_unimplemented
 
 if TYPE_CHECKING:
     from arcade.sprite_list import SpriteList
@@ -15,6 +16,7 @@
 SpriteType = TypeVar("SpriteType", bound="BasicSprite")
 
 
+@copy_dunders_unimplemented # See https://github.com/pythonarcade/arcade/issues/2074
 class BasicSprite:
     """
     The absolute minimum needed for a sprite.

arcade/sprite_list/sprite_list.py

@@ -38,6 +38,7 @@
 from arcade.gl.types import OpenGlFilter, BlendFunction, PyGLenum
 from arcade.gl.buffer import Buffer
 from arcade.gl.vertex_array import Geometry
+from arcade.utils import copy_dunders_unimplemented
 
 if TYPE_CHECKING:
     from arcade import Texture, TextureAtlas
@@ -53,6 +54,7 @@
 _DEFAULT_CAPACITY = 100
 
 
+@copy_dunders_unimplemented  # Temp fixes https://github.com/pythonarcade/arcade/issues/2074
 class SpriteList(Generic[SpriteType]):
     """
     The purpose of the spriteList is to batch draw a list of sprites.

arcade/utils.py

@@ -24,6 +24,7 @@
     "NormalizedRangeError",
     "PerformanceWarning",
     "ReplacementWarning",
+    "copy_dunders_unimplemented",
     "warning",
     "generate_uuid_from_kwargs",
     "is_raspberry_pi",
@@ -111,6 +112,55 @@ def __init__(self, var_name: str, value: float):
         super().__init__(var_name, value, 0.0, 1.0)
 
 
+_TType = TypeVar('_TType', bound=Type)
+
+def copy_dunders_unimplemented(decorated_type: _TType) -> _TType:
+    """Decorator stubs dunders raising :py:class:`NotImplementedError`.
+
+    Temp fixes https://github.com/pythonarcade/arcade/issues/2074 by
+    stubbing the following instance methods:
+
+    * :py:meth:`object.__copy__` (used by :py:func:`copy.copy`)
+    * :py:meth:`object.__deepcopy__` (used by :py:func:`copy.deepcopy`)
+
+    Example usage:
+
+    .. code-block:: python
+
+       import copy
+       from arcade,utils import copy_dunders_unimplemented
+       from arcade.hypothetical_module import HypotheticalNasty
+
+       # Example usage
+       @copy_dunders_unimplemented
+       class CantCopy:
+            def __init__(self, nasty_state: HypotheticalNasty):
+                self.nasty_state = nasty_state
+
+       instance = CantCopy(HypotheticalNasty())
+
+       # These raise NotImplementedError
+       this_line_raises = copy.deepcopy(instance)
+       this_line_also_raises = copy.copy(instance)
+
+
+    """
+    def __copy__(self):  # noqa
+       raise NotImplementedError(
+           f"{self.__class__.__name__} does not implement __copy__, but"
+           f"you may implement it on a custom subclass."
+       )
+    decorated_type.__copy__ =  __copy__
+
+    def __deepcopy__(self, memo):  # noqa
+       raise NotImplementedError(
+           f"{self.__class__.__name__} does not implement __deepcopy__,"
+           f" but you may implement it on a custom subclass."
+       )
+    decorated_type.__deepcopy__ = __deepcopy__
+
+    return decorated_type
+
 class PerformanceWarning(Warning):
     """Use this for issuing performance warnings."""
     pass

tests/unit/physics_engine/test_physics_engine2.py

@@ -1,4 +1,7 @@
 """ Physics engine tests. """
+import copy
+
+import pytest
 
 import arcade
 
@@ -287,6 +290,14 @@ def platformer_tests(moving_sprite, wall_list, physics_engine):
     assert moving_sprite.position == (3, -6)
 
 
+# Temp fix for https://github.com/pythonarcade/arcade/issues/2074
+def nocopy_tests(physics_engine):
+    with pytest.raises(NotImplementedError):
+        _ = copy.copy(physics_engine)
+    with pytest.raises(NotImplementedError):
+        _ = copy.deepcopy(physics_engine)
+
+
 def test_main(window: arcade.Window):
     character_list = arcade.SpriteList()
     wall_list = arcade.SpriteList()
@@ -303,9 +314,11 @@ def test_main(window: arcade.Window):
     physics_engine = arcade.PhysicsEngineSimple(moving_sprite, wall_list)
     basic_tests(moving_sprite, wall_list, physics_engine)
     simple_engine_tests(moving_sprite, wall_list, physics_engine)
+    nocopy_tests(physics_engine)
 
     physics_engine = arcade.PhysicsEnginePlatformer(
         moving_sprite, wall_list, gravity_constant=0.0
     )
     basic_tests(moving_sprite, wall_list, physics_engine)
     platformer_tests(moving_sprite, wall_list, physics_engine)
+    nocopy_tests(physics_engine)

tests/unit/physics_engine/test_pymunk.py

@@ -23,6 +23,18 @@ def test_pymunk():
     assert(my_sprite.center_y == -300.0)
 
 
+# Temp fix for https://github.com/pythonarcade/arcade/issues/2074
+def test_pymunk_engine_nocopy():
+    import copy
+    physics_engine = arcade.PymunkPhysicsEngine(
+        damping=1.0, gravity=(0, -100))
+
+    with pytest.raises(NotImplementedError):
+        _ = copy.copy(physics_engine)
+    with pytest.raises(NotImplementedError):
+        _ = copy.deepcopy(physics_engine)
+
+
 @pytest.mark.parametrize("moment_of_inertia_arg_name",
                          (
                              "moment_of_inertia",

tests/unit/shape_list/test_buffered_drawing.py

@@ -1,3 +1,6 @@
+import copy
+import pytest
+
 import arcade
 from arcade.shape_list import (
     ShapeElementList,
@@ -18,7 +21,9 @@
 SCREEN_HEIGHT = 600
 
 
-def test_buffered_drawing(window):
+@pytest.fixture
+def shape_list_instance() -> ShapeElementList:
+
     shape_list = ShapeElementList()
 
     center_x = 0
@@ -84,11 +89,35 @@ def test_buffered_drawing(window):
     shape = create_line_generic(points, arcade.color.ALIZARIN_CRIMSON, gl.GL_TRIANGLE_FAN)
     shape_list.append(shape)
 
-    shape_list.center_x = 200
-    shape_list.center_y = 200
+    return shape_list
+
+
+def test_shape_copy_dunders_raise_notimplemented_error(window, shape_list_instance):
+
+    for shape in shape_list_instance:
+        with pytest.raises(NotImplementedError):
+            _ = copy.copy(shape)
+        with pytest.raises(NotImplementedError):
+            _ = copy.deepcopy(shape)
+
+
+# Temp fix for https://github.com/pythonarcade/arcade/issues/2074
+def test_shapeelementlist_copy_dunders_raise_notimplemented_error(window, shape_list_instance):
+
+    with pytest.raises(NotImplementedError):
+        _ = copy.copy(shape_list_instance)
+
+    with pytest.raises(NotImplementedError):
+        _ = copy.deepcopy(shape_list_instance)
+
+
+def test_buffered_drawing(window, shape_list_instance):
+
+    shape_list_instance.center_x = 200
+    shape_list_instance.center_y = 200
 
     for _ in range(10):
-        shape_list.draw()
+        shape_list_instance.draw()
         window.flip()
         window.clear()
-        shape_list.move(1, 1)
+        shape_list_instance.move(1, 1)