Re: Coding for Multiple Implementaions for a service without named annotaions in GUICE

[Stephan Classen]

Question1 - 10+ implementations: If you have lots of implementation or you have a plugin like architecture where new implementations may be added after your main component has already been released then my proposed solution would not scale. If you are in such a situation have a look at multibinders: http://code.google.com/p/google-guice/wiki/Multibindings But if you are sure you will only have a very limited number of implementations and no new ones will be added after release day I would go with an approach similar to my proposal. Simply because I feel it is easier readable and most important it is testable without having to create an injector. Question2 - should it implement Provider<T>: I deliberately did not implement the provider interface. And if you would try to add it to my code you would get a compiler error. I prefer to pass the required data to make the decision which implementation to choose to the method getServiceFor(...). The provider interface on the other hand has only a no-arg method get(). If you would want to implement the provider interface you would have to inject all required information to make the decision into your implementation. This may lead to more complex code when the decision is based on a user action or similar information which is not available beforehand. I agree that in a guice based implementation the usage of the word provider in a class name may not be well suited if the class does not implement the provider interface. You could call the class OrganizationServiceFactory or OrganizationServiceLocator to avoid confusion. On 02/26/2014 03:35 PM, sreenivasu puppala wrote: I agree with you JP  , it would be very difficult to accomodate if there are hundred implementations , Please post me if you find any solution, iam in need of the code urgently :-) Thanks SCL, i have question I guess OrganizationServiceProvider should implement Provider in the below code? On Wednesday, February 26, 2014 11:38:57 AM UTC, Juan Pablo Vergara Villarraga wrote: I understand the solution from scl as a container for all the possible implementations of the dependency to be injected. It looks like a practical solution when there are few implementations. Would it be an elegant solution if we have a hundred implementations or so? Im currently coding a solution for this problem as well. If I find a different solution I'll post it :) JP El martes, 25 de febrero de 2014 03:06:34 UTC-5, scl escribió: public class OrganizationServiceProvider {      private final OrganizationServiceImpl orgService;      private final OrgDeatilsServiceImpl orgDetailService;      @Inject      OrganizationServiceProvider(final OrganizationServiceImpl orgService, final OrgDeatilsServiceImpl orgDetailService) {          this.orgService = orgService;          this.orgDetailService = orgDetailService;      }      public OrganizationService getServiceFor(/* you must pass the the necessary input to decide which impl to choose */) {          // your code goes here. it must return either orgService or orgDetailService      } } public class OrganizationsResource {      private final OrganizationServiceProvider osProvider;      @Inject      OrganizationsResource(final OrganizationServiceProvider osProvider) {          this.osProvider = osProvider;      }      // more code... } There is no special binding in the Guice module necessary since all injections go to concrete classes. Of course it would be nice to introduce an interface for OrganizationServiceProvider and have an OrganizationServiceProviderImpl. In this case you would need to bind the impl to the interface. -- You received this message because you are subscribed to the Google Groups "google-guice" group. To unsubscribe from this group and stop receiving emails from it, send an email to google-guice+unsubscr...@googlegroups.com. To post to this group, send email to google-guice@googlegroups.com. Visit this group at http://groups.google.com/group/google-guice. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups "google-guice" group. To unsubscribe from this group and stop receiving emails from it, send an email to google-guice+unsubscr...@googlegroups.com. To post to this group, send email to google-guice@googlegroups.com. Visit this group at http://groups.google.com/group/google-guice. For more options, visit https://groups.google.com/groups/opt_out.