APT tool

Question

Is this the right forum for the annotation processing tool (APT).
I will assume it is, since it has to do with meta data, which is related to reflection.
As I understand it, one of the purposes of the new annotations/metadata mechanism is to allow third party tools which can process java program which are annotated with meta data, see for example the @remote example in 1.5 in a nutshell.
However, I can not see how the @remote example can be brought to work, since the tool should translate
public class Ping {
   public @remote void ping() {
into
public interface PingIF extends Remote {
  public void ping() throws RemoteException;
public class Ping implements PingIF {
  public void ping() {
This means that the class Ping should be transformed into one which has an extra implements.
The APT explicitly states that it is a read only tool. That is fine. And I can see how I can write a new file, which contains the new Ping class.
But I can not see how that should be done if there was any code in the body of the original ping, I cannot using the current APT tool get hold of the method body (or the initializers of fields). This seems to be necessary for a long range of interesting tools.
-- Kasper

Answer 1

The only way that I can see to do what you need to do with apt is to use the Proxy design pattern. That is, your "annotation processor" can output the source for a Java class that wraps the one you're processing, and your wrapper class can throw RemoteExceptions and the like.
The only advantage of using apt over a doclet is that apt is more tightly integrated with javac. In particular, it will spawn off instances of the compiler to handle your machine-generated code. The real issue is that neither apt nor doclets solve the real problem---that you need to modify, not wrap, the source code based on the annotation. Apt does not provide access to the parse or abstract-syntax tree, so the only solution is to write a small compiler, yourself.
-Allen