Re: OO problem: Performing actions on messages (very long, sorry)

[Simon Wright <simon@pushface.org>]

"per" <commander@death-star.com> writes:

> I'm new to Ada (but not to OO). I'm having trouble designing a
> system, or at least a key part of it. (I have a few alternative
> non-tested solutions but I don't get why this doesn't work.) And I'd
> like to do it "by the book" in nice OO Ada coding style.

Nothing wrong with that, but you do need to get the right classes
(analyse the right problem? -- UML background coming out there!).

Seems to me you have a number of message specs; a message spec
consists of a (ordered) set of field specs; a field spec consists of a
type (and perhaps a size). It's here that you're going to hit "simple"
Ada types.

I'm not sure where your actions come in; are they related to a field
type, to a field in a message type, or a field in a particular
message?

Anyway, given a set of field specs in a message spec you can build up
a particular message (consisting of field _values_ corresponding to
the specs). And the action can do its thing when appropriate,

The message would (in my view) have a lot more to it than the bare
bytes that get sent to the equipment under test (I suspect you think
so too). What might be appropriate here is a convert-to-byte-stream
operation.

The advantage of a data-driven approach like this, if you can swing
it, is that adding new messages is only a matter of adding new message
type definitions, which are just data about messages.

Just my 2p --