Re: [aspectj-users] @Entity but not subclass of @Entity

[Simone Gianni <simoneg@xxxxxxxxxx>]

Hi Andy,
I think I didn't explain it clearly. I have

@Entity
public class Bean {

}

and a number of sub-beans :

@Entity
public class SubBean extends Bean {

}

How can I match Bean but not SubBean based on the @Entity annotation? 
That is, how can I write "A class annotated with @Entity which is NOT a 
subclass of another class annotated with @Entity".

Since the only "subclass" operator in AspectJ is the "+", which is 
inclusive, writing (@Entity *) && !((@Entity *)+) is useless, as it 
would be using an interface instead of (@Entity *).

If I had a construct to say "only subclasses" (suppose #, merely for 
illustrative purposes) I could write:
- (@Entity *) && ((@Entity *)#) to find only those entities which super 
class is also an entity
- (@Entity *) && !((@Entity *)#) to find only those classes which are 
entities but does not extend another entity
- (Bean) && !(Bean#), as a slower alternative to within(Bean).

Such an operator is not present cause it is (nearly) useless when only 
classes and interfaces are used, because :
- They are always inherited, as opposed to annotations
- Declaring an interface on a class and on one or more of its subclasses 
is (nearly) useless and has no strange side effects.
- Taking ITD methods with that interface would result in method 
overriding with same implementation, which is (usually) acceptable and 
invisible.

But annotations are more flexible from this point of view, and in this 
case I need a bit more flexibility.

Is there a way to emulate this?

The "if" pointcut could solve situations where we are advicing 
(if(!thisJoinPointStaticPart.getSignature().getDeclaringType().getSuperClass().hasAnnotation(Entity.class))) 
but not when we are declaring parents cause a TypePattern is required 
there, nor when we are declaring a warning cause "if" is not statically 
determinable.

Am I missing something relevant here?

Simone

Andy Clement wrote:
> Just to mention a possibly existing bug in this area to do with 
> annotation inheritance:
>
> https://bugs.eclipse.org/bugs/show_bug.cgi?id=128664
>
> Andy
>
> 2009/8/12 Simone Gianni <simoneg@xxxxxxxxxx <mailto:simoneg@xxxxxxxxxx>>
>
>     Hi All,
>     I have a problem. I add some methods to beans annotated with
>     @Entity. Some @Entity extends other @Entity, with the result that
>     methods are added to both types. I added a check to avoid adding
>     them if they are already there (using !hasmethod(...)), but it
>     works or does not work depending on the class loading sequence
>     (which is IMHO a bug I'll write another mail about).
>
>     Anyway, it could be easy to solve writing "Apply this to @Entity
>     beans that does not subclass another @Entity bean", I tried
>     writing "(@Entity *) && !((@Entity *)+)", but it does not work
>     obviously. I also tried an if on thisJoinPointStaticPart, but it
>     is not usable there.
>
>     Is there a way to do it? Is there an "exclusive +" that matches
>     subclasses but not also the base class? While it is handy to write
>     execution(MyClass+ .....) to match both class and subclass, and
>     while there is a way to select all subclasses when the class name
>     is known, I can't find a way to do it with annotations.
>
>     Simone
>
>     -- 
>     Simone Gianni            CEO Semeru s.r.l.           Apache Committer
>     http://www.simonegianni.it/
>
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--
Simone Gianni            CEO Semeru s.r.l.           Apache Committer
http://www.simonegianni.it/