[weld-dev] Automatic non contextual injection using bytecode instrumentation

[Mark Struberg]

not sure if this got solved in the meantime, but javaagent was pure pita when I tried it, since it doesn't work well with complicated classloader hierarchies. It always used the SystemClassLoader instead of the webapp classloaders where my JPA libs did reside. But maybe it was only my bad...

LieGrue,
strub

--- On Sun, 11/14/10, Marius Bogoevici <mariusb at redhat.com> wrote:

> From: Marius Bogoevici <mariusb at redhat.com>
> Subject: Re: [weld-dev] Automatic non contextual injection using bytecode instrumentation
> To: "Stuart Douglas" <stuart.w.douglas at gmail.com>
> Cc: "Weld" <weld-dev at lists.jboss.org>
> Date: Sunday, November 14, 2010, 11:08 PM
> I think it would be something nice to
> have. For example, Spring does this via @Configurable,
> backed by AspectJ. 
> 
> I think that exploring bytecode instrumentation would be
> interesting for Weld,and I have for some time considered the
> possibility of using it as an option for
> interception/decoration as well.
> 
> Regarding javaagent: for certain classloaders that support
> instrumentation and registering a ClassFileTransformer
> directly, we may forgo using a javaagent altogether and
> register the transformer during the bootstrap process. In
> the least, this would possible with Tomcat,
> Glassfish(partly) and JBoss.
> 
> On 2010-11-14, at 5:35 PM, Stuart Douglas wrote:
> 
> > I just had an idea for something that I think would be
> rather cool,
> > and allow objects created using new to be injected
> automatically.
> > 
> > Conceptually it would look something like this:
> > 
> > @AutoInject
> > public class AccountService
> > {
> >  private final Account account;
> > 
> >  @Inject
> >  private PaymentProcessor paymentProcessor;
> > 
> >  AccountService(Account account)
> >  {
> >    this.account = account;
> >  }
> > 
> >  public void doPayment(double amount)
> >  {
> >    paymentProcessor.processPayment(account,
> amount);
> >  }
> > }
> > 
> > We could then create the object using new and the
> fields will still be injected:
> > 
> > AccountService a = new AccountService(account);
> > a.doPayment(10);
> > 
> > To implement this will require a javaagent, which will
> modify the
> > bytecode of @AutoInject annotated classes as they are
> loaded, so that
> > the constructor bytecode looks up the values to inject
> and sets the
> > injected field values appropriately. Would this be
> something that is
> > worth putting into weld extensions?
> > 
> > Stuart
> > _______________________________________________
> > weld-dev mailing list
> > weld-dev at lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/weld-dev
> 
> 
> _______________________________________________
> weld-dev mailing list
> weld-dev at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/weld-dev
>