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From "Jochen Kemnade (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (TAP5-729) Tapestry IOC proxies have incorrect implementation when interface method uses a covariant return type (causes AbstractMethodError)
Date Mon, 03 Aug 2015 07:52:04 GMT

     [ https://issues.apache.org/jira/browse/TAP5-729?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jochen Kemnade resolved TAP5-729.
---------------------------------
    Resolution: Not A Problem

We'll assume that this is no longer a problem.

> Tapestry IOC proxies have incorrect implementation when interface method uses a covariant
return type (causes AbstractMethodError)
> ----------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: TAP5-729
>                 URL: https://issues.apache.org/jira/browse/TAP5-729
>             Project: Tapestry 5
>          Issue Type: Bug
>          Components: tapestry-ioc
>    Affects Versions: 5.1.0.5
>            Reporter: Paul Field
>              Labels: generics
>
> Here's a Junit 3 test case to demonstrate:
> import junit.framework.TestCase;
> import org.apache.tapestry5.ioc.Registry;
> import org.apache.tapestry5.ioc.RegistryBuilder;
> import org.apache.tapestry5.ioc.ServiceBinder;
> public class ProxyText extends TestCase {
>     private Registry registry;
>     @Override
>     protected void setUp() throws Exception {
>         RegistryBuilder builder = new RegistryBuilder();
>         builder.add(AppModule.class);
>         registry = builder.build();
>         registry.performRegistryStartup();
>     }
>     public void testRegistryWorks() {
>         assertEquals(new Integer(1), registry.getService(SuperIFace.class).get());
>     }
>     public static class AppModule {
>         public static void bind(ServiceBinder binder) {
>             binder.bind(IFace.class, Impl.class);
>         }
>     }
>     public interface SuperIFace {
>         Number get();
>     }
>     public interface IFace extends SuperIFace {
>         Integer get();
>     }
>     public static class Impl implements IFace {
>         public Integer get() {
>             return 1;
>         }
>     }
> }
> ----- 
> The result is:
> java.lang.AbstractMethodError: $IFace_1218d10684a.get()Ljava/lang/Number;
> Note that if you change SuperIFace to:
>     public interface SuperIFace {
>         Integer get();
>     }
> the test works - demonstrating that the problem is to do with the use of a covariant
return type in IFace.
> BTW, this has turned up in code for testing where I want to create sub-interfaces that
provide additional testing facilities for fake services and I need to control the particular
types that are returned by the fake implementation.



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