Merge pull request #134 from gilzoide/bugfix/invalid-object-handling

Fix handling of freed objects

Author: gilzoide

CHANGELOG.md

@@ -13,6 +13,7 @@
   MyScript.exported_int_valued_dict = export({ type = Dictionary[Variant][int] })
   MyScript.exported_texture_property = export({ type = Texture })
   ```
+- `is_instance_valid` utility function when opening `GODOT_UTILITY_FUNCTIONS` library
 
 ### Changed
 - `LuaScriptInstance`'s data table is passed as `self` to methods instead of their owner `Object`
@@ -26,6 +27,7 @@
   MyScript.exported_dictionary = export(Dictionary)
   ```
 - Convert null Object Variants (`<Object#null>`) to `nil` when passing them to Lua
+- Convert freed Object Variants (`<Freed Object>`) to `nil` when passing them to Lua
 
 
 ## [0.5.0](https://github.com/gilzoide/lua-gdextension/releases/tag/0.5.0)

src/luaopen/utility_functions.cpp

@@ -21,6 +21,7 @@
  */
 #include "../generated/utility_functions.hpp"
 #include "../utils/VariantArguments.hpp"
+#include "../utils/extra_utility_functions.hpp"
 #include "../utils/function_wrapper.hpp"
 #include "../utils/string_literal.hpp"
 #include "../utils/string_names.hpp"
@@ -119,6 +120,7 @@ extern "C" int luaopen_godot_utility_functions(lua_State *L) {
 	sol::state_view state = L;
 
 	register_utility_functions(state);
+	state.set("is_instance_valid", wrap_function(L, &is_instance_valid));
 
 	// In Lua, `print` separates passed values with "\t", so we bind it to Godot's `printt`
 	state.do_string("print = printt");

src/utils/convert_godot_lua.cpp

@@ -32,6 +32,7 @@
 #include "DictionaryIterator.hpp"
 #include "VariantArguments.hpp"
 #include "convert_godot_std.hpp"
+#include "extra_utility_functions.hpp"
 #include "load_fileaccess.hpp"
 #include "stack_top_checker.hpp"
 
@@ -184,7 +185,7 @@ sol::stack_object lua_push(lua_State *lua_state, const Variant& value) {
 			break;
 
 		case Variant::OBJECT:
-			if ((Object *) value == nullptr) {
+			if (!is_instance_valid(value)) {
 				sol::stack::push(lua_state, sol::nil);
 				break;
 			}

src/utils/extra_utility_functions.cpp

@@ -0,0 +1,33 @@
+/**
+ * Copyright (C) 2025 Gil Barbosa Reis.
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the “Software”), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is furnished to do
+ * so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#include "extra_utility_functions.hpp"
+
+#include <godot_cpp/variant/utility_functions.hpp>
+
+namespace luagdextension {
+
+bool is_instance_valid(const Variant& v) {
+	return v.get_type() == Variant::Type::OBJECT
+		&& UtilityFunctions::is_instance_id_valid(v.operator ObjectID());
+}
+
+}

src/utils/extra_utility_functions.hpp

@@ -0,0 +1,35 @@
+/**
+ * Copyright (C) 2025 Gil Barbosa Reis.
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the “Software”), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is furnished to do
+ * so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#ifndef __UTILS_EXTRA_UTILITY_FUNCTIONS_HPP__
+#define __UTILS_EXTRA_UTILITY_FUNCTIONS_HPP__
+
+#include <godot_cpp/variant/variant.hpp>
+
+using namespace godot;
+
+namespace luagdextension {
+
+bool is_instance_valid(const Variant& v);
+
+}
+
+#endif  // __UTILS_EXTRA_UTILITY_FUNCTIONS_HPP__

test/lua_tests/invalid_objects.lua

@@ -0,0 +1,8 @@
+assert(instance_from_id(0) == nil)
+
+assert(not is_instance_valid(nil))
+local node = Node:new()
+assert(is_instance_valid(node))
+node:free()
+assert(not is_instance_valid(node))
+