Custom metadata in AS3/Flex?

Question

How to create and to work with custom metadata in ActionScript3/Flex?

Answer 1

There is two general directions to deal with metadata in ActionScript in Flex:

1. Dealing in runtime using reflection (or introspection in terms of Adobe). You can find documentation here. There are several third-party libraries which provides more convenient reflection API such as as3-commons-reflect or reflection API in Parsley.
2. Using Flex Compiler Extensions which was introduced since Flex 4 SDK revision 8165 (see details). See also the corresponding discussion and official documentation.