[jsr294-modularity-eg] Fw: Nested superpackage visibility

[Glyn Normington]

Rather than continue the discussion in private, I'm forwarding the comment 
below from the observer who prompted this thread, Ulf Ochsenfahrt, for 
consideration and to create a public record of the responses.

I'll let Ulf introduce himself:
> Let me shortly introduce myself. My name is Ulf Ochsenfahrt, and I have 
> studied Computer Science in Rostock, Germany, and Stanford, US. As an 
> avid Java programmer, I have been following the JSR 294 mailing list 
> discussion.

Glyn
----- Forwarded by glyn_normington at uk.ibm.com on 28/06/07 02:54 PM -----

Ulf Ochsenfahrt <ulf at ofahrt.de> wrote on 28/06/2007 10:19:00 AM:

> Glyn Normington wrote:
> > 
> > Hi Ulf
> > 
> > Sibling nested superpackages can see each other's exported types. 
Would 
> > you like to reword your comment based on that?
> 
> That is a significant clarification, and it makes the proposal more 
> complex from a conceptual point of view. Instead of just a tree, the 
> structure becomes something like a tree, but not quite:
> 
>       a
>      / \
>    [b   c]
>    / \   \
> [d   e]  f
> 
> In the example, b and c form something like a subsystem (just like in 
> the 'subsystem' proposal), but without the flexibility.
> 
> The next question must of course be: Are superpackages allowed to access 

> their siblings children (nephews)? What about cousins?
> 
> The more superpackages are accessible, the weaker the proposal gets 
> (because there are more and more 'exceptions' to the tree structure), 
> and the more complex its conceptual model becomes.
> 
> What if a strict separation between b and c is desired? Then we need to 
> insert dummy nodes into that tree, such that b and c are not mutually 
> accessible any more.
> What if c is supposed to be able to access e? Then both e _and_ d have 
> to be pulled up to the level of b and c, even though d has nothing to do 

> with this (supposedly d and e access each other). Talk about 
brittleness!
> 
> The more superpackages are accessible, the more one must ask whether a 
> tree is a good idea to represent these kinds of relationships.
> 
> What do you think?
> 
> Cheers,
> 
> -- Ulf






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