Override built-in type method so SoundGroup instances can be identified

api.lua

@@ -93,6 +93,8 @@ SoundGroup = {
 				end
 			end
 
+			def.__type = "SoundGroup"
+
 			def.__init = {
 				-- execute "play" methode when called directly
 				__call = self.play,

init.lua

@@ -20,6 +20,7 @@ end
 
 
 local scripts = {
+	"override",
 	"api",
 	"groups",
 	"node_groups",

override.lua

@@ -0,0 +1,16 @@
+
+-- override built-in type function
+local otype = type
+type = function(obj)
+	local base_type = otype(obj)
+	if base_type == "table" then
+		local meta_type = otype(obj.__type)
+		if meta_type == "string" then
+			return obj.__type
+		elseif meta_type == "function" then
+			return obj:__type()
+		end
+	end
+
+	return base_type
+end