I think that Decorators are a great concept in CDI, but it cannot provide solution to a wide variety of problems where the general decorator pattern makes sense.

AFAIK, it is not possible to chain decorators at runtime, in order to reuse the decorator mechanism to solve class explosion problem and create a flexible architecture, similar to what java.io API provides with chained input/output streams (subclasses of java.io.InputStream).

I think it would make sense to be able to apply decorators to a bean at runtime.

What do you think about extending Instance class by adding a method like Instance<T> decorateWith(Class<?> c) as in the following example?

I haven't find a way to do something similar using the current API, nor did I find any third-party CDI extension to provide something similar.

Ondrej