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Date: Tue, 25 Nov 2008 03:27:45 +0100
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To: Marcus Boerger <helly@php.net>
Cc: Stefan Marr <php@stefan-marr.de>, internals@lists.php.net
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Subject: Re: [PHP-DEV] Grafts, Traits, horizontal reuse
From: christopher.vogt@rwth-aachen.de (Christopher Vogt)

Hej Marcus,

I like your approach. It is clear and simple. It would probably solve
90% of the cases, where delegation is needed.

I want to add that a manually defined method should automatically
overwrite a delegated method of the same name.

But I also want to bring up two reasonable situations your approach does
not cover. Your approach does not allow to delegate only a selection of
methods. This makes sense in order to limit the delegation to known
functionality. To stick to your example, without selective delegation,
new methods added to Counter would be automatically delegated to
CounterUser. This might break things.

A second situation not covered by your approach is renaming of delegated
methods. This can be desirable due to name clashes or name changes for
better understandability.

Of course there is always the fall back to manually implementing
delegation. And your approach alone would already be quite useful
syntactic sugar. But additional syntactic sugar for the two situations
described above would still be nice :).

Another thing. I am not sure if you intended that, but I think
delegation should not force using an Interface definition. Interfaces
are helpful in combination with type hinting, but for people who prefer
duck typing, it is reasonable to not explicitly define them. Let's leave
this choice to the people :).

Best regards

Christopher