Rules of Acquisition Must Be Declared

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In my last entry I mentioned XVCL. One peculiar feature of XVCL is that the scoping rules seems to be backwards. That is variables defined in the parent always override variables defined in the siblings.

I've seen this before in Ant and in Zope's inheritance via acquisition. For the configuration of object instances, the scoping rules of acquisition are crucial. The strangest thing though is that they all seem to be defined backwards.

I did some googling and found this piece that defines "Acquisition Algebra" and a seminal paper "Environmental Acquisition - A New Inheritance Mechanism". The paper observes:

The basic character of an object, sometimes called "behavior" in the OO jargon, is determined at birth (instantiation), and not by the household (the composite object) of which it is a part.

Stuart Halloway has wrote a piece on the inconsistency of java configuration. He proposes that Structure, Lookup, Scope and MetaData be well defined. He proposes that Lookup and Scope be defined by different providers and that MetaData be available to introspect the strucure. I would like to go one step further, that is the Rules of Acquisition be declarative.

That is just like XVCL, it should be easy to find and redefine how a component acquires its context.

Last modified 2003-08-05 06:50 AM