Re: XML DOM Binding for Ada 95 - matter of style

["Matthew Heaney" <matthewjheaney@earthlink.net>]

"Preben Randhol" <randhol+abuse@pvv.org> wrote in message
news:slrnbihv85.4jd.randhol+abuse@kiuk0152.chembio.ntnu.no...
> Marin David Condic wrote:
> > BTW: I never really liked the XMLAda approach of using discriminated
> > records and thought it should have been built in a more Object Oriented
> > way using tagged records.
>
> What is the gain?
>
> I thought one of the problems with Booch was that it was using tagged
> types too much. Does Charles also use this approach?

One problem is that you have to make two instantiations: one for the root
package, in which the root type is declared, and another, for the child
package in which the actual container (derived) type is declared.  This is a
royal pain.

Charles deliberately avoided this technique, because no inheritance is
necessary.  Static mechanisms are used instead, which are simpler and more
general.

So don't use a tagged type hierarchy when there's a simpler mechanism
available.  I haven't seen the XMLAda approach, but I am totally sympathetic
to approaches that do *not* use tagged records.

I'm not against tagged type ("object-oriented") programming, it's just that
many programmers seem to treat this as a hammer looking for a nail, and
automatically use a tagged type to solve a problem that is better solved
other ways.

Look for a new release of Charles early next week.

http://home.earthlink.net/~matthewjheaney/charles/