[jsr294-modularity-eg] Runtime model

[Glyn Normington]

Andreas Sterbenz <Andreas.Sterbenz at sun.com> wrote on 14/06/2007 06:35:48 
PM:

> Glyn Normington wrote:
> > 
> > Further to my comments below, I'd like us to explore why loading a 
> > legacy class into a superpackage would be deemed to be changing, 
rather 
> > than compatibly extending, its semantics?
> 
> Sure. I think we should start by examining the use cases. Some of the 
> questions in my mind are:
> 
> When is it is necessary to dynamically draft legacy classes into the 
> superpackage?

To allow applications to support multiple versions of Java and exploit 
superpackages on Java 7. We should remember that at least in the first few 
years of Java 7, the world will be mainly at Java 5 or 6 and application 
writers won't want to restrict their market to a fraction of the total.

If we don't support this use case, then the only applications that will 
exploit superpackages are those which are being written from scratch or 
rewritten specifically for Java 7. This will be a small minority of 
applications until the world is mainly at Java 7 in, perhaps, a decade or 
so.

> 
> Why are approaches that expose classes that are a member of a 
superpackage 
> and legacy classes as one "component" (module, bundle, etc.) not 
> sufficient? They can coexist just fine.

Agreed, but this would delay the uptake of superpackages.

> 
> Another approach is static class file rewriting. When is that not 
sufficient?

Whether this use case is supported by re-defining the semantics of 
existing compiled code or automatically re-writing the classes is a detail 
we can work out if we agree we should support the use case. I agree class 
rewriting is probably sufficient, but I'm not sure the significant extra 
complexity is necessary.

Glyn

> 
> Andreas.
> 
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