Re: Pointers explained?

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Mon, 30 Jul 2007 10:53:16 -0700, shaunpatterson@gmail.com wrote:

> 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;

Are you sure that you want to copy messages? Let there are 10000
subscribers to a messages publisher. Then upon emitting a message you will
copy it 10000 times!

I would consider:

type CallbackEvent (Message : access Message'Class) is

> 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:

No problem, leave factory as-is, returning Message'Class. Whenever you
would need to allocate Message, you could still do it like this:

    new Message'Class'(Factory (...));

Factory returns Message'Class used to initialize the memory allocated for
the new object.

> type CallbackEvent is
> record

You could consider making reference counted Messages and handles to them.
Handles will be copied around and placed into containers like
CallbackEvent.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de