From: benjohn@...
Date: 2006-10-02T20:46:26+09:00
Subject: Re: Creating modules

I wrote before about the modules I'm trying to build on the fly. I'm
going to describe it a bit more and see if anyone has a thought about
what I should be doing here, because I'm not making much ground. [Using
modules was my latest foray in the direction of another approach, but I
think I've given up on that avenue]

What I have are messages and parameters. I'll concentrate on parameters.

Parameters - I have instances of a parameter. Each parameter is an
instance of a type of parameter.

There are about 20 known types of parameter. I must also support unknown
types of parameter (which I will generate on the fly and furnish with
minimal generic behaviour). The known parameters fall in to two groups:
those that have a simple encoding and those with more complex encoding.
To sumarise, the types of parameter have a hierarchy:

ParameterType
UnknownParamerType < ParameterType
KnownParameterType < ParameterType
SimpleParameterType < KnownParameterType
ComplexParameterType < KnownParameterType

Remember that instances of these parameter types are not actual
parameters, they are the classes that parameters instances fall in to.

At the moment, I have a sepererate class for Parameter. Instances of
this delegate to a ParameterType instance. This is annoying me though:
it seems more complex than it ought to be.

I've tried quite a few approaches to putting all this together, but
nothing seems to fit the problem very well.

Any thoughts? Sorry if the above isn't very clear!

Cheers,
  Benjohn Barnes

p.s. I think this lends some support to prototype based information models.