Re: [aspectj-dev] Introducing a method to classes that are in the JRE

["Wes Isberg" <wes@xxxxxxxxxxxxxx>]

You could set up a map from the object to its encoding.  
The aspect would set up the map, use advice to make the
association, and then use advice to change to
locale-specific behavior.  Unfortunately, this costs 
a map lookup for all instances of the type for
the association and for any uses.  

Wes

P.S. - If the locale is always the same for a given
control flow, you can also make that association with a
percflow aspect, and avoid the map lookup.

aspect ManagingStringsWithLocale { // untested
   // warning: sync, map, intern, memory issues 
   // with this code - consider before use!

   final Map stringToLocale = new HashMap();


   before(Locale locale, String s) : ... {
       if (null == stringToLocal.get(s)) {
            stringToLocal.put(s, locale);
       }
   }

   String around(String s) : target(s) &&
           call(String toLowerCase()) {
       Locale locale = (Locale) stringToLocal.get(s);
       if (null == locale) {
           return proceed(s);
       } else {
           return s.toLowerCase(locale);
       }
   }
}



On Tue, 2 Dec 2003 15:51:54 -0800
 jerry_liu@xxxxxxxxxxx wrote:
> What I had wanted to do was be able to annotate instances
> of Java classes and then act on these instances based on
> the annotation.  The actual application is too complex to
> describe, but here's a contrived example which captures
> the flavor.
> 
> Say I have a text processing system where String
> (java.lang.String) objects were being passed around.  I
> want to be able to tag the language encoding of the
> String to the String object.  Since String is final, I
> can't subclass it, and since all my processing code act
> on 'String', I can't make a MyString object which wraps a
> String.
> 
> I was hoping to be able to use AspectJ to introduce a
> 'language' attribute, and associated methods, to the
> String class, and in effect add this little bit of
> annotation to the String objects.  Getting around the
> 'final' keyword, so to speak...
> 
> Is there another way to do this with Aspects?
> 
> Thanks,
> 
> Jerry
> 
> > -----Original Message-----
> > From: aspectj-dev-admin@xxxxxxxxxxx
> > [mailto:aspectj-dev-admin@xxxxxxxxxxx]On Behalf Of Wes
> Isberg
> > Sent: Tuesday, December 02, 2003 12:39 PM
> > To: aspectj-dev@xxxxxxxxxxx
> > Subject: Re: [aspectj-dev] Introducing a method to
> classes that are in
> > the JRE
> > 
> > 
> > The mechanics of doing something like this are 
> > described in the Programmer's Guide discussion of
> > inter-type declaration and the Development Environment
> > Guide section on the ajc tool -injars option.  Both
> > are linked off the AspectJ documentation page.
> > 
> > But we recommend against modifying Java classes because
> 
> > doing violates the spirit and perhaps the letter of
> Sun's
> > license.  Further, I think it unwise to modify final
> > classes, and believe that AspectJ should avoid this
> > (perhaps permitting it under the rubric of privilege):
> > 
> >   https://bugs.eclipse.org/bugs/show_bug.cgi?id=47919
> > 
> > If you can specify the code you'd actually like to
> > write and what you're trying to do, then perhaps 
> > someone can help you do it another way.
> > 
> > Wes
> > 
> > On Tue, 2 Dec 2003 10:56:59 -0800
> >  jerry_liu@xxxxxxxxxxx wrote:
> > > Are there any tips on how I can introduce methods and
> > > attributes to a class like java.lang.Integer which is
> > > packaged in the Java runtime?  Or pointers to a FAQ
> if
> > > this is a known question.  I'm new to this. :-)
> > > 
> > > Thanks,
> > > 
> > > Jerry
> > > _______________________________________________
> > > aspectj-dev mailing list
> > > aspectj-dev@xxxxxxxxxxx
> > > http://dev.eclipse.org/mailman/listinfo/aspectj-dev
> > 
> > _______________________________________________
> > aspectj-dev mailing list
> > aspectj-dev@xxxxxxxxxxx
> > http://dev.eclipse.org/mailman/listinfo/aspectj-dev
> > 
> _______________________________________________
> aspectj-dev mailing list
> aspectj-dev@xxxxxxxxxxx
> http://dev.eclipse.org/mailman/listinfo/aspectj-dev