A utility for enforcing some singleton prefix on objects in GameMaker. The default prefix is "the", i.e. `the_singletonName`.

object_is_singleton.gml

gml_pragma("global", @'
        // search for singletons
        global.singletons = ds_list_create();
        for (var i = 0; object_exists(i); i++) {
            if (object_prefix(i) == SINGLETON_PREFIX) {
                ds_list_add(global.singletons, i);
                // automatically insert singleton into the first room
                object_set_persistent(i, true);
                room_instance_add(room_first, 0, 0, i);
            }
        }');
#macro SINGLETON_PREFIX "the"
/// @desc Returns whether an object is a singleton
/// @param obj {Integer} The id of the object to check.
/// @author Kat @katsaii
if (is_real(argument0) && !object_exists(argument0) &&
        instance_exists(argument0)) then argument0 = argument0.object_index;
return ds_list_find_index(global.singletons, argument0) != -1;

object_prefix.gml

/// @desc Returns the object prefix
/// @param obj {Integer} The id of the object to check.
/// @author Kat @katsaii
var obj = argument0;
if (is_real(obj) && !object_exists(obj) &&
        instance_exists(obj)) then obj = obj.object_index;
var name = object_get_name(obj);
var pos = string_pos("_", name);
return pos == -1 ? "" : string_copy(name, 1, pos - 1);