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Message-Id: <5.1.0.14.2.20021207205720.00bb06f8@mail.sutic.nu>
Date: Sat, 07 Dec 2002 21:03:58 +0100
To: avalon-dev@jakarta.apache.org
From: Leo Sutic <leo.sutic@inspireinfrastructure.com>
Subject: Locators (was: Re: Context: usage recommendations?)
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Stephen wrote:
 >  * Service locator
 >
 >    This is a new concept that is very similar to the
 >    Merlin extension handler.  It a component that provides
 >    a plug-in lookup solution that can be narrowed to a
 >    particular interface (and can be located by the container
 >    using the interface name as the key). A service locator
 >    can be applied to the following three areas:
 >
 >      * context value lookup
 >      * service lookup
 >      * lifecycle stage handler lookup

If you have two interfaces:

interface A {
   void method ();
}

interface B {
   void method ();
}

and a dynamic proxy (or any class) implementing both interfaces:

class Proxy implements A, B {
    ...
}

Proxy proxy = ...;

The two calls:

((A) proxy).method ();
((B) proxy).method ();

are indistiguishable. This is true even if you are using a dynamic proxy's
InvocationHandler. (In which case they will both be calls to A.method.)

Unlike C#, Java has no way of distinguishing through what interface the
call was made.

I think this makes your idea less useful.

(Yes, I have a proposal of my own, writing it right now...)

/LS


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