One could take this problem to another direction. The problem, it
seems, is the fact that you must pass a parameter to the Logger about
the class (or type) of the injectee. There is a way to accomplish
this, but it won't be pretty :)
public class LoggerFor<T> {
@Inject private TypeLiteral<T> injectee;
public Logger passMeTheLogger() { return Logger.getLogger
(injectee.getRawType()); }
}
Then, suppose you want to use a logger in the following class:
public class LoggerUser {
@Inject private LoggerFor<LoggerUser> please;
public void doesSomething() {
Logger logger = please.passMeTheLogger();
logger.debug("thanks!");
}
}
There is the obvious drawback: now you have to bind a LoggerFor<T> for
every of its clients.
-- Rodrigo Couto
On 25 jul, 14:17, Adrian Cole <[email protected]> wrote:
> Indeed you are correct. I believe this is the only way to accomplish
> the goal with the current version of guice without hacking core
> classes. I don't think this was possible at all in Guice 1.0.
>
> For this to be accomplished natively, one way could be to add a
> context to providers. In this context, one could reach the injectee
> like below:
>
> @Provider Logger providerLogger(InjectionContext context){
> return Logger.getLogger(context.getInjectee().getClass().getName());
>
> }
>
> I'm interested in other opinions on how to accomplish this.
>
> Regards,
> -Adrian
> jclouds
>
> On Sat, Jul 25, 2009 at 4:51 PM, Gili Tzabari<[email protected]> wrote:
>
> > Hi Adrian,
>
> > If I understand your code directly, you always inject
> > Logger.getRootLogger() into the constructor, then use reflection to
> > alter the field after-the-fact to the current type. Is this correct?
>
> > I'm looking for a way to set the Constructor argument to the right
> > value in the first place, instead of fixing it after the fact. It seems
> > to me that Guice 2.0 is missing a facility for this sort of thing. Are
> > there any plans for adding one in Guice 2.1 or 3.0?
>
> > Thanks,
> > Gili
>
> > Adrian Cole wrote:
> >> Hi, Gili.
>
> >> I've just coded this for you.. I hope you digg it ;)
>
> >>http://digg.com/d3yXEh
>
> >> Cheers,
> >> -Adrian
> >> jclouds
>
> >> On Fri, Jul 24, 2009 at 2:22 PM, Gili Tzabari<[email protected]>
> >> wrote:
> >>> Guys,
>
> >>> I don't understand your answers. It sounds to me like you're
> >>> talking
> >>> about field injection, not constructor injection.
>
> >>> I don't want to inject a log into an already-constructed object. I
> >>> want
> >>> to inject a log directly into the class constructor:
>
> >>> class Foo
> >>> {
> >>> private final Logger log;
>
> >>> @Inject
> >>> public Foo(Logger log)
> >>> {
> >>> this.log = log;
> >>> }
> >>> }
>
> >>> Also, I am not necessarily doing this for jdk loggers so please
> >>> provide
> >>> more detail on how to write a custom injection listener to do this.
>
> >>> Thanks,
> >>> Gili
>
> >>> Adrian Cole wrote:
> >>>> If just injecting a log class, you're right: that's trivial. The
> >>>> less trivial part is setting the log scope relevant to the object
> >>>> being constructed.
>
> >>>> -Adrian
>
> >>>> On Fri, Jul 24, 2009 at 10:51 AM, Dhanji R. Prasanna<[email protected]>
> >>>> wrote:
> >>>>> You can also write a trivial injection listener that looks for whatever
> >>>>> logging class you like and set it after construction.
> >>>>> Dhanji.
>
> >>>>> On Fri, Jul 24, 2009 at 5:49 PM, Adrian Cole <[email protected]> wrote:
> >>>>>> In jclouds, we use a similar approach, but don't bind ourselves to
> >>>>>> java or log4j:
> >>>>>> http://code.google.com/p/jclouds/wiki/LogDesign
>
> >>>>>> Here's the configuration class that may help you do what you are
> >>>>>> looking
> >>>>>> for:
>
> >>>>>>http://code.google.com/p/jclouds/source/browse/trunk/core/src/main/ja...
>
> >>>>>> I hope this helps,
> >>>>>> -Adrian
> >>>>>> jclouds
>
> >>>>>> On Fri, Jul 24, 2009 at 6:15 AM, Dhanji R. Prasanna<[email protected]>
> >>>>>> wrote:
> >>>>>>> You can already do this with jdk loggers.
> >>>>>>> Dhanji.
>
> >>>>>>> On Fri, Jul 24, 2009 at 2:12 PM, Gili <[email protected]> wrote:
> >>>>>>>> Hi,
>
> >>>>>>>> Is it possible to implement Log4JMembersInjector -- as found here:
> >>>>>>>>http://code.google.com/p/google-guice/wiki/CustomInjections-- but for
> >>>>>>>> constructor injection instead? That is, I'd like Guice to be smart
> >>>>>>>> enough to inject the correct Logger instance into the constructor
> >>>>>>>> automatically. I took a look at InjectionListener but it seems to
> >>>>>>>> hook
> >>>>>>>> instances that have already been injected. Another approach that
> >>>>>>>> comes
> >>>>>>>> to mind is:
>
> >>>>>>>> @Provides
> >>>>>>>> public Logger getLogger(Class<?> outerClass);
>
> >>>>>>>> If I could somehow get Guice to pass in the correct Class... Any
> >>>>>>>> ideas?
>
> >>>>>>>> Gili
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