sigh mixin: refine auto signals

TODO

@@ -37,3 +37,4 @@ TODO:
 * view and view iterator specializations for multi, single and filtered elements
 * organizer support to groups
 * meta range: move id to meta objects and return plain types (?), then remove id from meta base and meta ctor too
+* doc: automatic signal registration

src/entt/entity/mixin.hpp

@@ -14,34 +14,25 @@ namespace entt {
 /*! @cond TURN_OFF_DOXYGEN */
 namespace internal {
 
-template<typename T, typename Reg, typename = void>
+template<typename, typename, typename = void>
 struct has_on_construct final: std::false_type {};
 
-template<typename T, typename Reg>
-struct has_on_construct<
- T, Reg,
- std::void_t<decltype(T::on_construct(std::declval<Reg &>(),
- std::declval<Reg &>().create()))>>
+template<typename Type, typename Registry>
+struct has_on_construct<Type, Registry, std::void_t<decltype(Type::on_construct(std::declval<Registry &>(), std::declval<Registry>().create()))>>
  : std::true_type {};
 
-template<typename T, typename Reg, typename = void>
+template<typename, typename, typename = void>
 struct has_on_update final: std::false_type {};
 
-template<typename T, typename Reg>
-struct has_on_update<
- T, Reg,
- std::void_t<decltype(T::on_update(std::declval<Reg &>(),
- std::declval<Reg &>().create()))>>
+template<typename Type, typename Registry>
+struct has_on_update<Type, Registry, std::void_t<decltype(Type::on_update(std::declval<Registry &>(), std::declval<Registry>().create()))>>
  : std::true_type {};
 
-template<typename T, typename Reg, typename = void>
+template<typename, typename, typename = void>
 struct has_on_destroy final: std::false_type {};
 
-template<typename T, typename Reg>
-struct has_on_destroy<
- T, Reg,
- std::void_t<decltype(T::on_destroy(std::declval<Reg &>(),
- std::declval<Reg &>().create()))>>
+template<typename Type, typename Registry>
+struct has_on_destroy<Type, Registry, std::void_t<decltype(Type::on_destroy(std::declval<Registry &>(), std::declval<Registry>().create()))>>
  : std::true_type {};
 
 } // namespace internal

test/entt/entity/sigh_mixin.cpp

@@ -18,6 +18,24 @@
 #include "../../common/throwing_allocator.hpp"
 #include "../../common/throwing_type.hpp"
 
+struct auto_signal final {
+ inline static void on_construct(const entt::registry &, entt::entity) {
+ ++created;
+ }
+
+ inline static void on_update(entt::registry &, const entt::entity) {
+ ++updated;
+ }
+
+ inline static void on_destroy(entt::registry &, entt::entity) {
+ ++destroyed;
+ }
+
+ inline static std::size_t created{};
+ inline static std::size_t updated{};
+ inline static std::size_t destroyed{};
+};
+
 template<typename Registry>
 void listener(std::size_t &counter, Registry &, typename Registry::entity_type) {
  ++counter;
@@ -625,3 +643,30 @@ TEST(SighMixin, ThrowingComponent) {
  ASSERT_EQ(on_construct, 2u);
  ASSERT_EQ(on_destroy, 3u);
 }
+
+TEST(SighMixin, AutoSignal) {
+ entt::registry registry;
+ auto const entity = registry.create();
+
+ registry.emplace<auto_signal>(entity);
+ registry.replace<auto_signal>(entity);
+ registry.erase<auto_signal>(entity);
+
+ ASSERT_EQ(auto_signal::created, 1u);
+ ASSERT_EQ(auto_signal::updated, 1u);
+ ASSERT_EQ(auto_signal::destroyed, 1u);
+
+ ASSERT_TRUE(registry.storage<auto_signal>().empty());
+ ASSERT_TRUE(registry.valid(entity));
+
+ registry.emplace<auto_signal>(entity);
+ registry.replace<auto_signal>(entity);
+ registry.destroy(entity);
+
+ ASSERT_EQ(auto_signal::created, 2u);
+ ASSERT_EQ(auto_signal::updated, 2u);
+ ASSERT_EQ(auto_signal::destroyed, 2u);
+
+ ASSERT_TRUE(registry.storage<auto_signal>().empty());
+ ASSERT_FALSE(registry.valid(entity));
+}