Re: Windows Ada database support.

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

On Thu, 9 Dec 2004 12:20:38 +0000 (UTC), Georg Bauhaus wrote:

> Dmitry A. Kazakov <mailbox@dmitry-kazakov.de> wrote:

>: We have tasks and protected objects. Add here marshaling parameters. So you
>: will need by-value semantics for types of those. Hence, allow T'Class for
>: everything. You will then need interface inheritance from concrete types
>: (to have automatic user-defined type conversions between local and remote
>: types). That drags MI. Do not forget to make tasks and protected objects
>: OO. Something like COM/DCOM will be also very useful...
> 
> And you end up with the problems of value copying (and externally stored
> data).

First, they are *not* stored. They exist. Second, it is impossible to have
referential semantics for everything, just because reference itself has to
be by-copy.

> Have a lookt at purely functional programs. :-) Time, memory,
> updates, and concurrent updates, are not your friend when you prefer
> good abstractions :-)

I didn't mean that. Yes we have to marshal the parameters. But it by no
means imply that we should marshal everything. It is up to the application
to decide what should be passed by-copy and what by-reference (handle). It
is no different from what happens when you compile a procedure call in Ada.
Protected objects are by-reference in Ada. The difference though is that in
a distributed application physical location of an object may change. So the
run-time should be able to move an object from one place to another, to
make a replica of it etc.

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