Re: No overloading of types by the number of type parameters

From:
Piotr Kobzda <pikob@gazeta.pl>
Newsgroups:
comp.lang.java.programmer
Date:
Wed, 11 Jul 2007 14:54:39 +0200
Message-ID:
<f72juj$tv$1@inews.gazeta.pl>
Stefan Ram wrote:

  Now, I needed to apply it as follows


Alternatively, you can define a marker (non generic) Domain interface
and various (generic or not) interfaces extending it, for example:

public interface Domain {}

public interface D1<P1> extends Domain {
     P1 getP1();
     void setP1(P1 value);
}
public interface D2<P1,P2> extends D1<P1> {
     P2 getP2();
     void setP2(P2 value);
}
public interface D3<P1,P2,P3> extends D2<P1,P2> {
     P3 getP3();
     void setP3(P3 value);
}
/* and so on...*/

And then have a single action interface defined that way:

public interface ParametrizedAction<D extends Domain> {
     void of(D domain);
}

The actions then might be implemented as follows:

public class AgentStreamAction
         implements ParametrizedAction<D2<HttpURLConnection,InputStream>>
{
     public void of(D2<HttpURLConnection,InputStream> domain) {
         of(domain.getP1(), domain.getP2());
     }

     public void of(HttpURLConnection connection, InputStream stream) {
         /*...*/
     }
}

That above "domains" model might be nicely supported with reflection,
for e.g. generic abstract Action class implementing "of(Domain)" method,
or some utility classes like Proxy-based universal domains implementation.

piotr

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