Re: [aspectj-users] Selecting arithmetic operation join points. Is it po

[Alexander Kriegisch <Alexander@xxxxxxxxxxxxxx>]

There is no operator overloading in Java. It is implemented in other JVM languages like Scala, but this is a bit off-topic here.

BTW, I did not say it was impossible, just that it will probably never happen in AspectJ. ;) What you show is normal method interception, not operator interception. Smthe example is not really relevant. Besides, you never know what a compiler might do with arithmetic operations optimisation-wise. Multiplication by powers of 2 might get replaced by left-shift operations (just making up an example). I do not even say that what you suggest might not be useful in so e rare and special cases, I just think it is way to fine-granular for AOP purposes. I think your example is rather academic than useful in daily work.

Alexander Kriegisch

Am 07.01.2013 um 10:34 schrieb "M. P." <freebsd@xxxxxx>:

>>> For example I'd like to be able to select integer subtraction:
> 
> 
>>> Integer i = 5;
> 
>>> Integer j = 2;
> 
>>> Integer r = i - j;
> 
> 
>>> Maybe if Java supported operator overloading that would be fairly easy.
> 
> 
>>> 1. So is something like this possible now? I'm pretty sure it is not.
> 
> 
>> You are right, it is not possible.
> 
> 
>>> 2. Would this be possible to implement? How? Effort?
> 
>>> 3. Is something like this planned for future AspectJ versions?
> 
> 
>> I cannot speak for the developers, but I do not think you will ever see this feature in AspectJ.
> 
> 
> 
> 
>> Regards
> 
> 
> I'm not sure I see why not. Please consider the following example:
> 
> public aspect StringConcat {
>     public pointcut concat() : call(* java.lang.StringBuffer.append(..));
>     
>     before() : concat() {
>         System.out.println("About to concatenate!");
>     }
> }
> 
> public class Tester {
> 
>     public static void main(String[] args) {
>         String a = "a";
>         String b = "b";
>         System.out.println(a + b);
>     }
> }
> 
> When main() is executed the result is:
> =======================
> About to concatenate!
> ab
> =======================
> 
> So we actually have a real example where the + operator is overloaded and the resulting code is directly in the client byte code.
> Now I'm not too familiar with the Java byte code spec but I don't see why the same cannot be done for e.g. Integer or event the primitive types?
> 
> Thank you.
> 
> MP
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