Re: [aspectj-users] Implementing abstract pointcut that includes nojoinp

[Ken Pelletier <ken@xxxxxxxx>]

Thanks for all the quick replies.

Oddly, I did try the pointcut with not spec:

protected pointcut overriddenAbstractPointcut();

But because I'd missed on the parameter matching (the abstract decl  
captures the target for around advice which I'd left off in the sub),  
I mistakenly thought that the syntax was generally incorrect.

So, it's actually the first thing that came to mind, which is always  
a good feeling.

It's also good to see that this can be done in the base aspect; sort  
of a parallel with the template method pattern, only for pointcuts  
and advice.  Good stuff.

Thanks,

- Ken

On Oct 21, 2005, at 12:24 AM, Ron Bodkin wrote:

> Ken,
>
> This syntax will do it, although it is a little counterintuitive  
> when you
> first encounter it:
>
> protected pointcut overriddenAbstractPointcut();
>
> You can also define a default empty value in a concrete pointcut  
> (like this)
> in an abstract aspect and then override it with a non-empty  
> definition in
> some concrete aspects. E.g.,
>
> abstract aspect Base {
>    protected pointcut optionalPoint(); // empty
> }
>
> aspect Derived1 extends Base {
>    protected pointcut optionalPoint() : within(foo..*); // defines  
> for this
> }
>
> aspect Derived2 extends Base {
>    // optional is empty for this concrete aspect
> }
>
> -----Original Message-----
> From: aspectj-users-bounces@xxxxxxxxxxx
> [mailto:aspectj-users-bounces@xxxxxxxxxxx] On Behalf Of Ken Pelletier
> Sent: Thursday, October 20, 2005 10:06 PM
> To: aspectj-users@xxxxxxxxxxx
> Subject: [aspectj-users] Implementing abstract pointcut that includes
> nojoinpoints
>
> I have an abstract aspect that declares a couple of abstract
> pointcuts to be overridden in concrete subclasses.
>
> In a particular subclass, however I want to nullify one of those
> pointcuts; include no joinpoints at all.
>
> Is there a common idiom for implementing a concrete pointcut that
> explicitly includes no joinpoints?
>
> I know I can nullify with && if(false), but it smells funny to
> declare any advice type at all if really none applies.
>
> Eg:
>
> protected overriddenAbstractPointcut() :
> <what_would_advice_spec_be_here> && if(false;
>
> Regards,
>
> - Ken
>
> PS: it's probably a design smell in the first place to have abstract
> pointcuts that sometimes have no applicable concrete implementation,
> but that's another matter.  :-)
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