Re: Ada OOP alternatives?

["(see below)" <yaldnif.w@blueyonder.co.uk>]

On 17/07/2008 02:36, in article wccy741fg0z.fsf@shell01.TheWorld.com,
"Robert A Duff" <bobduff@shell01.TheWorld.com> wrote:

> "(see below)" <yaldnif.w@blueyonder.co.uk> writes:
> 
>> On 17/07/2008 01:05, in article wcc3am9gytt.fsf@shell01.TheWorld.com,
>> "Robert A Duff" <bobduff@shell01.TheWorld.com> wrote:
>>> I'd still rather eliminate private parts altogether.
>> 
>> How would you do that while allowing ADT clients to access objects directly
>> (i.e. not via a pointer a la Java)?
> 
> I'd have the compiler take a peek at the body when compiling the client.
> After all, that's what Ada compilers already do for pragma Inline.

Good point.
That does induce a bit more compile-time overhead, though, as all clients
would have to be recompiled on every update to the body.

> And I think incremental compilation can be a big win.
> In fast-compile mode, I might tolerate the "via pointer" way.
> It doesn't need to be a pointer into the heap, as in Java.
> 
> We're just talking about the size of the type, really -- you say
> "access objects", but clients can't access the record components
> of a private type -- all they can do is declare objects and
> pass them around.

And copy them.
Yes, but to do that well, they need to know at least the size of the
representation.
 
> Java, like many languages, doesn't even _have_ separate specs.
> (And it _still_ insists on pointers for almost everything!)

I loathe the Java type system's incoherence.

> So it's clearly feasible to have information in bodies used
> when compiling clients.

Certainly.

To what extent do you think that the (optical) visibility of the
representation in the Ada private part offsets a need to give the client's
programmer a more formal statement of the semantics of the ADT?
-- 
Bill Findlay
<surname><forename> chez blueyonder.co.uk