 		}
 
 		public function mapClass(
-			whenAskedFor : Class, instantiateClass : Class, named : String = null) : void
+			whenAskedFor : Class, instantiateClass : Class, named : String = "") : void
 		{
 			var config : InjectionConfig = new InjectionConfig(
 				whenAskedFor, instantiateClass, InjectionConfig.INJECTION_TYPE_CLASS);
 			addMapping(config, named);
 		}
 		
-		public function mapSingleton(whenAskedFor : Class, named : String = null) : void
+		public function mapSingleton(whenAskedFor : Class, named : String = "") : void
 		{
 			mapSingletonOf(whenAskedFor, whenAskedFor, named);
 		}
 
 		public function mapSingletonOf(
-			whenAskedFor : Class, useSingletonOf : Class, named : String = null) : void
+			whenAskedFor : Class, useSingletonOf : Class, named : String = "") : void
 		{
 			var config : InjectionConfig = new InjectionConfig(
 				whenAskedFor, useSingletonOf, InjectionConfig.INJECTION_TYPE_SINGLETON);

			return instance;
		}
		
		public function unmap(clazz : Class, named : String = null) : void
		{
			var requestName : String = getQualifiedClassName(clazz);
			if (named && m_mappings[named])

		}

		public function mapValue(
			whenAskedFor : Class, useValue : Object, named : String = "") : void
		{
			var config : InjectionConfig = new InjectionConfig(
				whenAskedFor, useValue, InjectionConfig.INJECTION_TYPE_VALUE);
