Assuming you need to inject stuff into DispatchHandler and you don't want
Dispatcher to know about DispatchHandler's deps, here's how I would do it.
public class Dispatcher {
private final DispatchHandler.Factory handlerFactory;
// package-private for unit testing
@Inject Dispatcher(DispatchHandler.Factory handlerFactory) {
this.handlerFactory = handlerFactory;
}
...
public boolean dispatch() {
for(PredictorProfile predictor : predictors) {
handlerFactory.newInstance(predictor).start();
}
return true;
}
}
public class DispatchHandler extends Thread {
private DispatchHandler(PredictorProfile predictor, Dep1 d1, ...) { ... }
...
public static class Factory {
private final Dep1 d1;
...
// package-private so we can unit test easily.
@Inject Factory(Dep1 d1, ...) { ... }
...
public DispatchHandler newInstance(PredictorProfile predictor) {
return new DispatchHandler(predictor, d1, ...);
}
}
}
You could also use "Builder" instead of "Factory" depending on how you
structure things. Needing this additional class is unfortunate but necessary
unless we extend the language to better support this stuff.
Bob
On Thu, Oct 16, 2008 at 9:02 AM, Andrew Clegg <[EMAIL PROTECTED]>wrote:
>
> Hey folks,
>
> I'm just getting started with Guice (and DI in general). I have a
> question, hope it's not too dense.
>
> I have a method that looks something like this in its first
> incarnation (_predictors is a collection):
>
> public boolean dispatch()
> {
> for( PredictorProfile predictor : _predictors )
> {
> Thread handler = new DispatchHandler( predictor );
> handler.run();
> }
> return true;
> }
>
> i.e. for each predictor that the object knows about, kick off a thread
> to process it, and then return. (The return true is just a placeholder
> for a proper status code later.)
>
> Now I've started to think Guicily, I don't like the look of that call
> to new. Everything else in this app so far is injected for me by
> Guice.
>
> What's the best pattern for this kind of situation?
>
> Thanks!
>
> Andrew.
>
> >
>
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