RE: [aspectj-users] Custom JoinPoints

["Wes" <wes@xxxxxxxxxxxxxx>]

 

Matthew Webster wrote:

 

In your example below the two invocations of go() are separate join points

 

doh, obviously.

 

>  the JoinPoint instance is passed as a argument to the advice method

> so is on the stack and so cannot be collected.

 

But the VM can treat any unreachable reference as eligible for GC.  Something can

be on the stack passed as a parameter but unreachable to executing code.  And as I

pointed out, the programmer need not set it to null for the VM to conclude it won't be

used again, but it can help.

 

>>Currently the same join point instance is shared by multiple advice
>>in different aspects.
> Correct, but this would have to change and any aspect associated with a custom

> JoinPoint factory would get its own custom instances. How else would you support

> multiple custom factories?

 

I wouldn't support one or many custom join point factories if it

involved breaking the AspectJ programmer's model, which I believe

includes sharing both state and changes to that state.  So the multiple

join-point instances should look like one instance: same hashcode

for advice on the same join point (arguable), and context changes

are visible to less-precedent code (required).  So the fact that

at the start of the join point the different join point instances

refer to the same context variable doesn't help when a client

of one of the join point instances replaces a reference in a

proceed(..) statement.  Less-precedent advice of all aspects should

see that different reference.

 

Wes