RE: [xml-dev] Discover data patterns or Create data patterns?

["Michael Kay" <mike@saxonica.com>]

> "Type" as people use the term in software languages, has an 
> idea of mutual exclusivity between primitive
> types: so that a string is not an integer for example.

One of the nicest systems I came across from a modelling perspective was
HP's IRIS database (subsequently OpenODB?), which allowed objects to be
instances of any number of types, and to gain and lose types dynamically. So
an employee can become a pensioner without changing identity, and can also
be a local councillor at the same time. A document can become a product if
someone decides to start selling it. Once you've played with that, the more
traditional object models start to feel very constraining.

At a purely practical level, I'm constantly wishing I could dynamically
change an ArrayList into a LinkedList without having to know about all the
places that might hold a reference to it. 

Michael Kay
http://www.saxonica.com/