Added LuaUserData.HasMember and made CreateStatic automatically add call metatable if it the type has a constructor

Barotrauma/BarotraumaShared/Lua/LuaUserData.lua

@@ -21,6 +21,7 @@ luaUserData.AddField = clrLuaUserData.AddField
 luaUserData.RemoveMember = clrLuaUserData.RemoveMember
 luaUserData.CreateUserDataFromDescriptor = clrLuaUserData.CreateUserDataFromDescriptor
 luaUserData.CreateUserDataFromType = clrLuaUserData.CreateUserDataFromType
+luaUserData.HasMember = clrLuaUserData.HasMember
 
 luaUserData.RegisterType = function(typeName)
 	local success, result = pcall(clrLuaUserData.RegisterType, typeName)
@@ -50,6 +51,10 @@ luaUserData.AddCallMetaTable = function (userdata)
 		error("Attempted to add a call metatable to a nil value.", 2)
 	end
 
+	if not LuaUserData.HasMember(userdata, ".ctor") then
+		error("Attempted to add a call metatable to a userdata that does not have a constructor.", 2)
+	end
+
 	debug.setmetatable(userdata, {
 		__call = function(obj, ...)
 			if userdata == nil then
@@ -68,14 +73,22 @@ luaUserData.AddCallMetaTable = function (userdata)
 	})
 end
 
-luaUserData.CreateStatic = function(typeName, addCallMethod)
+luaUserData.CreateStatic = function(typeName)
+	if type(typeName) ~= "string" then
+		error("Expected a string for typeName, got " .. type(typeName) .. ".", 2)
+	end
+
 	local success, result = pcall(clrLuaUserData.CreateStatic, typeName)
 
 	if not success then
 		error(result, 2)
 	end
 
-	if addCallMethod then
+	if result == nil then
+		return
+	end
+
+	if LuaUserData.HasMember(result, ".ctor")  then
 		luaUserData.AddCallMetaTable(result)
 	end
 

Barotrauma/BarotraumaShared/SharedSource/LuaCs/Lua/LuaClasses/LuaUserData.cs

@@ -284,6 +284,38 @@ namespace Barotrauma
             descriptor.RemoveMember(memberName);
         }
 
+        public static bool HasMember(object obj, string memberName)
+        {
+            if (obj == null) { throw new ScriptRuntimeException("object is nil"); }
+
+            Type type;
+            if (obj is Type)
+            {
+                type = (Type)obj;
+            }
+            else if(obj is IUserDataDescriptor descriptor)
+            {
+                type = descriptor.Type;
+
+                if (((StandardUserDataDescriptor)descriptor).HasMember(memberName))
+                {
+                    return true;
+                }
+            }
+            else
+            {
+                type = obj.GetType();
+            }
+
+            if (type.GetMember(memberName).Length == 0)
+            {
+                return false;
+            }
+
+            return true;
+        }
+
+
         /// <summary>
         /// See <see cref="CreateUserDataFromType"/>.
         /// </summary>