Skip side-effects on equal assignments

Fix relation components were not invalidated on changes.

Author: HexDecimal

CHANGELOG.md

@@ -10,6 +10,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `tcod.ecs.typing.ComponentKey` is now stable.
 - Can now register a callback to be called on component changes.
 
+### Fixed
+- Fixed stale caches for relation components.
+
 ## [4.2.1] - 2023-07-28
 ### Fixed
 - Unpickled worlds had reversed relations from what were saved.

tcod/ecs/entity.py

@@ -334,6 +334,8 @@ def __setitem__(self, key: ComponentKey[T], value: T) -> None:
 
         if old_value is None:
             tcod.ecs.query._touch_component(self.entity.world, key)  # Component added
+        elif old_value == value:
+            return
 
         self.entity.world._components_by_entity[self.entity][key] = value
         self.entity.world._components_by_type[key][self.entity] = value
@@ -682,8 +684,15 @@ def __getitem__(self, target: Entity) -> T:
     def __setitem__(self, target: Entity, component: T) -> None:
         """Assign a component to the target entity."""
         world = self.entity.world
-        if target in world._relation_components_by_entity[self.entity][self.key] is not None:
-            del self[target]
+
+        old_value = world._relation_components_by_entity[self.entity][self.key].get(target)
+        if old_value is None:  # Relation added
+            tcod.ecs.query._touch_relations(
+                world, ((self.key, target), (self.key, ...), (self.entity, self.key, None), (..., self.key, None))
+            )
+        elif old_value == component:
+            return
+
         world._relation_components_by_entity[self.entity][self.key][target] = component
 
         world._relations_lookup[(self.key, target)] = {self.entity}
@@ -716,6 +725,10 @@ def __delitem__(self, target: Entity) -> None:
         if not world._relations_lookup[(..., self.key, None)]:
             del world._relations_lookup[(..., self.key, None)]
 
+        tcod.ecs.query._touch_relations(
+            world, ((self.key, target), (self.key, ...), (self.entity, self.key, None), (..., self.key, None))
+        )
+
     def __iter__(self) -> Iterator[Entity]:
         """Iterate over the targets with assigned components."""
         by_entity = self.entity.world._relation_components_by_entity.get(self.entity)

tests/test_ecs.py

@@ -239,8 +239,10 @@ def test_tag_query() -> None:
     world = tcod.ecs.World()
     assert not set(world.Q.all_of(tags=["A"]))
     world["A"].tags.add("A")
+    world["A"].tags.add("A")  # Cover redundant add
     assert set(world.Q.all_of(tags=["A"])) == {world["A"]}
     world["A"].tags.remove("A")
+    world["A"].tags.discard("A")  # Cover redundant discard
     assert not set(world.Q.all_of(tags=["A"]))
 
 

tests/test_relations.py

@@ -74,9 +74,14 @@ def test_relation_components() -> None:
 
     entity_a.relation_components[int] = {world[1]: 1, world[2]: 2}
     entity_a.relation_components[int] = entity_a.relation_components[int]
+    entity_a.relation_components[int][world[1]] = 1
+
+    assert set(world.Q.all_of(relations=[(int, world[1])])) == {entity_a}
 
     entity_a.relation_components.clear()
 
+    assert not set(world.Q.all_of(relations=[(int, world[1])]))
+
 
 def test_conditional_relations() -> None:
     world = tcod.ecs.World()