This is VERY flexible ! And tricky too. Thanks a lot for your time :)
*---------------------* *Muhammad Gelbana* http://eg.linkedin.com/in/mgelbana/ On Mon, Sep 30, 2013 at 1:41 PM, Thiago H de Paula Figueiredo < thiag...@gmail.com> wrote: > Hello, Muhammad! > > > On Sat, 28 Sep 2013 07:37:37 -0300, Muhammad Gelbana <m.gelb...@gmail.com> > wrote: > > The last paragraph on that >> page<http://tapestry.apache.**org/service-advisors.html<http://tapestry.apache.org/service-advisors.html> >> >, >> states the following: >> >> *If you do, decoration take precedence; all decorators will be in effect >> >>> before any advice (internally, they are two separate steps, with advice >>> being processed and the result of that used by the decorators).* >>> >> >> >> At first, it states that decoration take precedence, then it states that >> internally, the advice is applied and the results is passed to the >> decorator. >> >> Is this paragraph contradicting it self ? >> > > It's a hard to understand paragraph, maybe because the concept itself is a > little hard to understand at first. When I first read it, I thought there > was a contradiction, but then I thought again, a light bulb appeared over > my head and I realized it does make sense. > > If you have a decorator D and an advice A on service D on method m (not > tested): > > public interface S { > int a(int parameter); > } > > public class Implementation implements S { > public int m(int parameter) { > System.out.println("S.m: " + parameter); > return parameter; > } > } > > public class D implements S { > final private S delegate; > public D(S delegate) { > this.delegate = delegate; > } > public int m(int parameter) { > System.out.println("D.m"); > int result = delegate.m(parameter); > System.out.println("D.m: result: " + result); > } > } > > public class Advice implements MethodAdvice { > public void advice(MethodInvocation invocation) { > System.out.println("A.m"); > // calls the advised method > invocation.proceed(); > // let's change the result value > int result = invocation.getReturnValue(); > System.out.println("A.m: result:" + result); > invocation.setReturnValue(**result * 2); > } > } > > If we call S.a(1), the output would be this: > > D.m > A.m > S.m: 1 > A.m: result: 1 > D.m: result: 2 > > The key concept here is that both service decoration and advice allow you > to add code *both* before *and* after the decorated or advised original > method. So the decorator takes precedence and its code is run before the > advice *and* after the advice. > > -- > Thiago H. de Paula Figueiredo > > ------------------------------**------------------------------**--------- > To unsubscribe, e-mail: > users-unsubscribe@tapestry.**apache.org<users-unsubscr...@tapestry.apache.org> > For additional commands, e-mail: users-h...@tapestry.apache.org > >
