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Subject: Re: Celix services and struct inheritance
From: Marcel Offermans <marcel.offermans@luminis.nl>
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Date: Thu, 26 Jan 2012 13:36:34 +0100
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To: <celix-dev@incubator.apache.org>

On Jan 26, 2012, at 13:19 PM, Pepijn Noltes wrote:

> I have a problem relating to Celix services and inheritance. The
> problem is than under Java it's quite normal to cast retrieved
> services to a derived type, but under C this is not as easy and not
> safe (no RTTI ->no instanceof).

Even though in Java you can (try to) cast a class or interface to a =
derived type, when you lookup a service in the OSGi service registry, it =
is extremely unwise to assume anything other than the fact that you just =
got an instance that implements exactly the interface you looked up.

> [...] But I am not really happy with this solution. It leans to much =
on the
> assumption service pointer can be cast to derived type and there is no
> way to check if this is correct.

Agreed.

> In my opinion there are 2 alternative to this:
> 1)
> Register multiple services. But than means I am left with the
> challenge how to find the related service.

In Java, you already have the option of registering an instance under =
multiple service names. Would doing the same for C solve your issue?

Greetings, Marcel