Re: Interface design problem

From:
Tom Anderson <twic@urchin.earth.li>
Newsgroups:
comp.lang.java.programmer
Date:
Tue, 26 Aug 2008 09:46:03 +0100
Message-ID:
<Pine.LNX.4.64.0808260940440.30818@urchin.earth.li>
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On Tue, 25 Aug 2008, Stefan Ram wrote:

Royan <romayankin@gmail.com> writes:

public interface IFileSystem {
public char[] readFile() throws IOException;
public interface INetwork {
public char[] readFile() throws IOException, RemoteException;


interface System< E extends java.lang.Throwable >
{ public char[] readFile() throws java.io.IOException, E; }

interface FileSystem extends System< java.lang.RuntimeException >{}

interface NetworkSystem extends System< java.rmi.RemoteException >{}


That doesn't really help, because you have to throw away polymorphism to
do it. If you write a program around FileSystem or System<IOException>,
you won't be able to substitute NetworkSystem in its place. You'd have to
genericise your client code, and write it all in terms of System<E>, which
would be a headache.

I'd take the approach of forcing the remote exceptions through the same
exception types as other exceptions. If the RemoteException is the one
from java.rmi, that's trivial, because it's already a subclass of
IOException. If it's a user-defined exception, i'd make it a subclass of
IOException. If you're feeling like overcomplicating things, you could
define a new FileSystemException, and have subclasses for the various
kinds of failure - FileNotFoundException, RemoteCommunicationException,
etc.

tom

--
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