Re: [aspectj-users] Progress on privileged support for annotation style

[Andrew Eisenberg <andrew@xxxxxxxxxxxx>]

One of the benefits of using annotation style aspects is that the
aspect classes can all be compiled with a standard Java compiler
before being passed to an aspect weaver.  This is extremely useful in
some situations.  But the downside is that Java compilation rules
cannot be subverted in the same way that we can do it in ajc.

So, the only way we can add this kind of privileged access to the
compiler would be through the JCP.  However, I believe it would be
difficult to convince many people to go along with it because it
violates accessibility rules, one of the fundamental precepts of Java.

In AspectJ, this violation is considered OK, but only if used with
care under the privileged keyword.  I don't want to dismiss your idea,
but I think it would be hard to move this philosophy to another
language.

--a

On Tue, Jan 27, 2009 at 7:44 AM, Neale Upstone <neale.upstone@xxxxxxxxxx> wrote:
> Hi,
>
>
>
> Has any progress been made on solving the issues of privileged access to
> aspects?
>
>
>
> For example, if I have a class:
>
> public class A {
>
>       private int i;
>
> }
>
>
>
> and aspect:
>
>
>
> @Aspect
>
> public class AspectA {
>
>
>
>       // set i after constructor has returned
>
> @AfterReturning("this(a) && execution(public *.new(..))")
>
>       public void setI( A a ){
>
>             a.i = 42;
>
>       }
>
> }
>
>
>
> then we will get a 'not visible' error for the assignment to i.
>
>
>
>
>
> It seems to me that it would be generally useful, outside of AspectJ too, to
> be able to tell the compiler/editor to allow access to private, protected
> and package scope objects.
>
>
>
> This would be done by changing the function to:
>
>
>
>       public void setI( @PrivilegedAccess('private') A a ){
>
>             a.i = 42;
>
>       }
>
>
>
>
>
> In fact, this would probably equate to an annotation-based 'friend'
> capability that C++ boasts of.
>
>
>
> Naturally, the passing of references would have to be dealt with, but this
> should be possible.  It may also allow annotations and an APT plugin to be
> used rather than having to work around security when doing reflection on
> object graphs, for example.
>
>
>
> The benefit of standardising something like this is that it would (with
> agreement with Sun et al) allow a standard compiler to support this.  The
> consequences, however, may be rather too scary!
>
>
>
> Cheers,
>
>
>
> Neale
>
>
>
>
>
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