Put some order to addProperty, also added __destruct metamethod for n…

…on luau

Source/LuaBridge/detail/CFunctions.h

@@ -7,6 +7,7 @@
 #pragma once
 
 #include "Config.h"
+#include "ClassInfo.h"
 #include "Errors.h"
 #include "FuncTraits.h"
 #include "LuaHelpers.h"
@@ -577,7 +578,7 @@ inline int read_only_error(lua_State* L)
  * @brief __tostring metamethod for a class.
  */
 template <class C>
-static int tostring_metamethod(lua_State* L)
+int tostring_metamethod(lua_State* L)
 {
     const void* ptr = lua_topointer(L, 1);
 
@@ -593,13 +594,46 @@ static int tostring_metamethod(lua_State* L)
     return 1;
 }
 
+//=================================================================================================
+/**
+ * @brief __destruct metamethod for a class.
+ */
+template <class C>
+int destruct_metamethod(lua_State* L)
+{
+    LUABRIDGE_ASSERT(lua_isuserdata(L, 1)); // Stack: userdata (ud)
+    const auto top = lua_gettop(L);
+
+    const int result = lua_getmetatable(L, 1); // Stack: ud, object metatable (ot) | nothing
+    if (result == 0)
+        return 0;
+
+    LUABRIDGE_ASSERT(lua_istable(L, -1)); // Stack: ud, ot
+
+    lua_rawgetp(L, LUA_REGISTRYINDEX, detail::getClassRegistryKey<C>()); // Stack: ud, ot, registry metatable (rt) | nil
+    if (lua_istable(L, -1)) // Stack: ud, ot, rt
+    {
+        rawgetfield(L, -1, "__destruct"); // Stack: ud, ot, rt, ud, function | nil
+        if (lua_isfunction(L, -1))
+        {
+            lua_pushvalue(L, 1); // Stack: ud, ot, rt, function, ud
+            lua_pcall(L, 1, 0, 0); // Stack: ud, ot, rt
+        }
+    }
+
+    lua_settop(L, top); // Stack: ud
+    return 0;
+}
+
 //=================================================================================================
 /**
  * @brief __gc metamethod for a class.
  */
 template <class C>
-static int gc_metamethod(lua_State* L)
+int gc_metamethod(lua_State* L)
 {
+    destruct_metamethod<C>(L);
+
     Userdata* ud = Userdata::getExact<C>(L, 1);
     LUABRIDGE_ASSERT(ud);
 
@@ -1064,6 +1098,26 @@ int invoke_proxy_constructor(lua_State* L)
     return 1;
 }
 
+//=================================================================================================
+/**
+ * @brief lua_CFunction to call on a object constructor via functor (lambda wrapped in a std::function).
+ *
+ * The proxy std::function (lightuserdata) is in the first upvalue. The class userdata object will be pushed at the top of the Lua stack.
+ */
+template <class F>
+int invoke_proxy_destructor(lua_State* L)
+{
+    using FnTraits = function_traits<F>;
+
+    LUABRIDGE_ASSERT(isfulluserdata(L, lua_upvalueindex(1)));
+
+    auto& func = *align<F>(lua_touserdata(L, lua_upvalueindex(1)));
+
+    function<void, typename FnTraits::argument_types, 1>::call(L, func);
+
+    return 1;
+}
+
 //=================================================================================================
 /**
  * @brief lua_CFunction to resolve an invocation between several overloads.
@@ -1887,6 +1941,31 @@ struct constructor_forwarder
     F m_func;
 };
 
+//=================================================================================================
+/**
+ * @brief Constructor forwarder.
+ */
+template <class T, class F>
+struct destructor_forwarder
+{
+    explicit destructor_forwarder(F f)
+        : m_func(std::move(f))
+    {
+    }
+
+    void operator()(lua_State* L)
+    {
+        auto* value = Userdata::get<T>(L, -1, false);
+        if (value == nullptr)
+            raise_lua_error(L, "invalid object destruction");
+
+        std::invoke(m_func, value);
+    }
+
+private:
+    F m_func;
+};
+
 //=================================================================================================
 /**
  * @brief Constructor forwarder.

Source/LuaBridge/detail/Namespace.h

@@ -932,6 +932,26 @@ class Namespace : public detail::Registrar
             return *this;
         }
 
+        //=========================================================================================
+        template <class Function>
+        auto addDestructor(Function function)
+            -> std::enable_if_t<detail::is_callable_v<Function>, Class<T>&>
+        {
+            static_assert(detail::function_arity_excluding_v<Function, lua_State*> == 1);
+            static_assert(std::is_same_v<detail::function_argument_t<0, Function>, T*>);
+
+            assertStackState(); // Stack: const table (co), class table (cl), static table (st)
+
+            using F = detail::destructor_forwarder<T, Function>;
+
+            lua_newuserdata_aligned<F>(L, F(std::move(function))); // Stack: co, cl, st, upvalue
+            lua_pushcclosure_x(L, &detail::invoke_proxy_destructor<F>, className, 1); // Stack: co, cl, st, function
+
+            rawsetfield(L, -3, "__destruct"); // Stack: co, cl, st
+
+            return *this;
+        }
+
         //=========================================================================================
         /**
          * @brief Add or replace a factory.

Tests/Source/ClassTests.cpp

@@ -645,6 +645,34 @@ struct ClassFunctions : ClassTests
 {
 };
 
+#if !LUABRIDGE_ON_LUAU
+TEST_F(ClassFunctions, Destructor)
+{
+    using Int = Class<int, EmptyBase>;
+
+    bool called = false;
+    int data = 0;
+
+    luabridge::getGlobalNamespace(L)
+        .beginClass<Int>("Int")
+            .addConstructor<void(int)>()
+            .addDestructor([&](Int* obj)
+            {
+                called = true;
+                data = obj->data;
+            })
+        .endClass();
+
+    runLua("local x = Int(42)");
+    ASSERT_TRUE(result().isNil());
+
+    closeLuaState();
+
+    EXPECT_TRUE(called);
+    EXPECT_EQ(42, data);
+}
+#endif
+
 TEST_F(ClassFunctions, MemberFunctions)
 {
     using Int = Class<int, EmptyBase>;

Tests/Source/IssueTests.cpp

@@ -223,7 +223,7 @@ TEST_F(IssueTests, IssueMainThread)
         .beginClass<SomeClass>("SomeClass")
         .addConstructor<void (*)(lua_State*)>()
         .addFunction("SomeMember", &SomeClass::SomeMember)
-        .addProperty("SomeMemberOverride", &SomeClass::override_)
+        .addProperty("SomeMemberOverride", &SomeClass::override_, &SomeClass::override_)
         .endClass();
 
     const char* source = R"(

Tests/Source/LegacyTests.cpp

@@ -237,10 +237,10 @@ void addToState(lua_State* L)
         .addFunction("getName", &A::getName)
         .addFunction("testSucceeded", &A::testSucceeded)
         .addFunction("__add", &A::operator+)
-        .addProperty("testProp", &A::testProp)
+        .addProperty("testProp", &A::testProp, &A::testProp)
         .addProperty("testProp2", &A::testPropGet, &A::testPropSet)
         .addStaticFunction("testStatic", &A::testStatic)
-        .addStaticProperty("testStaticProp", &A::testStaticProp)
+        .addStaticProperty("testStaticProp", &A::testStaticProp, &A::testStaticProp)
         .addStaticProperty("testStaticProp2", &A::testStaticPropGet, &A::testStaticPropSet)
         .endClass()
         .deriveClass<B, A>("B")

Tests/Source/Tests.cpp

@@ -1005,8 +1005,8 @@ TEST_F(LuaBridgeTest, Exception)
 
     luabridge::getGlobalNamespace(L)
         .beginNamespace("ns")
-            .addProperty("cb1", &cb1)
-            .addProperty("cb2", &cb2)
+            .addProperty("cb1", &cb1, &cb1)
+            .addProperty("cb2", &cb2, &cb2)
         .endNamespace();
 
     auto text = R"(