Pointers explained?

[shaunpatterson@gmail.com]

Hi

   I'm still relatively new to Ada -- coming from a strong C++
background.  Some of this may seem stupid - and feel free to point it
out to me.  I am using Ada 95 - GNAT Pro 3.16a1


I have a message factory I've been screwing around with (converting it
from Ada to C++).

I basically have an abstract message type:

type Message is abstract tagged null record;
type Message_Class is access all Message'Class;


then all other messages are derived from this.

Now from my factory create method, I'm returning a Message_Class.
This message_class
is stored in another record to be handled again later:

type CallbackEvent is
record
     msg : Message_Class;
     ...
end record;


Now my basic problem -- or not really a problem -- is that to create
the Message_Class I have to use
"new" and allocate and deallocate memory.

Now - my solution was to re-write my message factory to return a type
Message'Class.  However, I went
to change my callback structure to:

type CallbackEvent is
record