Re: Imitation is the sincerest form of flattery

[amir@iae.nsk.su (Amir Yantimirov)]

"Frank J. Lhota" <NOSPAM.lhota.adarose@verizon.net> wrote in message news:<6Y_fa.5102$kU.534@nwrdny01.gnilink.net>...
> "Amir Yantimirov" <amir@iae.nsk.su> wrote in message
> news:5115eb96.0303242148.57027600@posting.google.com...
> 
> > Not that. I propose something alike this:
> >
> > type TFoo = record ... end record;
> >
> > procedure Bar ( Baz : in out TFoo);
> >   with TFoo:
> >     'First = 1;
> >     'Last = 32;
> >     [].Read = ReadBits;
> >     [].Write = WriteBits;
> >   end with;
> > begin
> >   Baz[40] := 0; -- compile error!
> 
> I'm a little confused by this pseudo-code. Is Bar a derived type? Is it some
> sort of constructor? And what does the "[].Write = WriteBits;" statement do?
> You may very well have a quite valuable idea here, but this code sample does
> not convey it. Now that you have piqued our curiousity, please clarify.

It is a poor attempt to show how can looks addition of array interface
with fixed index bounds (so compiler can do range check) to already
defined type and inside some scope (procedure Bar). I never used Ada
and attempt to make example looks Ada-like only adds confusion.

The previous poster wrote that extending of type interface exist only
in dynamic languages as Smalltalk and don't allow compile time checks
and I tried to show that (theoretically) compiler is capable to do
this statically if necessary information is provided.

More of that here:
http://www174.pair.com/yamir/programming/interfaces.htm

In a short, I think it is a serious restriction that we use one
language construct (type/class) for description of two completely
different things - concrete information storage and abstract behaviour
interface.

Amir Yantimirov