Will there always be one implementation and only one implementation for the lifetime of the project? If so, can you decide upon that implementation during runtime before the Injector is created? If so, include the appropriate module to bind the ServiceImpl you want based on the configuration. If the impl can change throughout the lifetime (because users can request different types based on the 'type'), then you'll absolutely need some form of indirection (in your code the Factory provides the indirection). If you're concerned about calling new Service1 & new Service2, you can use BindingAnnotations to actually bind both kinds of Services, the Factory can have both Services injected and then hand out the appropriate service based on the 'type'.
Sam On Wed, Nov 18, 2009 at 12:02 AM, Ryan <[email protected]> wrote: > Hello everyone, > > I'm new to Guice (really enjoying it, by the way), but have come up > against a need and I'm not sure the most Guice-appropriate way to do > it. Done a lot of searching (including in this group), but am not > sure I found the solution. (Or perhaps I just didn't understand it.) > In any case, my question is how to select an implementation based on > some runtime value. For reference, a standard factory solution would > look like: > > class ServiceFactory { > public static Service get(int type) { > if(type == 1) { return new ServiceImpl1(); } > else if (type == 2) { return new ServiceImpl2(); } > } > } > > class Client { > public void process(int type) { > Service service = ServiceFactory.get(type); > } > } > > Feels too service locator-y. But I can think of no way to do this in > Guice except to inject the factory: > > class Client { > @Inject > ServiceFactory factory; > > public void process(int type) { > Service service = factory.get(type); > } > } > > class ServiceFactoryProvider implements Provider<ServiceFactory> { > @Override > public ServiceFactory get() { > return new ServiceFactory(); > } > } > > class MyModule extends AbstractModule { > @Override > protected void configure() { > bind(Client.class); > } > } > > What am I missing here? What's the proper way to implement this with > Guice? I don't think BindingAnnotations will work for me here, > because the implementation is decided upon at runtime, but feel free > to correct me. > > Thank you! > Ryan > > -- > > You received this message because you are subscribed to the Google Groups > "google-guice" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]<google-guice%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/google-guice?hl=. > > > -- You received this message because you are subscribed to the Google Groups "google-guice" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-guice?hl=.
