allow for return from new func CallLuaEventReturn

Source/lua/lua_event.cpp

@@ -32,6 +32,26 @@ void CallLuaEvent(std::string_view name, Args &&...args)
 	SafeCallResult(fn(std::forward<Args>(args)...), /*optional=*/true);
 }
 
+template <typename T, typename... Args>
+T CallLuaEventReturn(T defaultValue, std::string_view name, Args &&...args)
+{
+	sol::table *events = GetLuaEvents();
+	if (events == nullptr) {
+		return defaultValue;
+	}
+
+	const auto trigger = events->traverse_get<std::optional<sol::object>>(name, "trigger");
+	if (!trigger.has_value() || !trigger->is<sol::protected_function>()) {
+		return defaultValue;
+	}
+	const sol::protected_function fn = trigger->as<sol::protected_function>();
+	sol::object result = SafeCallResult(fn(std::forward<Args>(args)...), /*optional=*/true);
+	if (result.is<T>()) {
+		return result.as<T>();
+	}
+	return defaultValue;
+}
+
 void MonsterDataLoaded()
 {
 	CallLuaEvent("MonsterDataLoaded");

assets/lua/devilutionx/events.lua

@@ -24,17 +24,13 @@ local function CreateEvent()
     ---
     ---The arguments are forwarded to handlers.
     ---@param ... any
+    ---@return any
     trigger = function(...)
-      local args = {...}
-      if #args > 0 then
-        for _, func in ipairs(functions) do
-          func(table.unpack(args))
-        end
-      else
-        for _, func in ipairs(functions) do
-          func()
-        end
+      local result
+      for _, func in ipairs(functions) do
+        result = func(...)
       end
+      return result
     end,
     __sig_trigger = "(...)",
   }