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From: "Matthew Heaney" <mheaney@on2.com>
Newsgroups: comp.lang.ada
References: <311c6b78.0409271138.1795d07c@posting.google.com>
Subject: Re: An improved Ada?
Date: Mon, 27 Sep 2004 16:40:40 -0400
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Date: 2004-09-27T20:29:52+00:00
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"jn" <jonas.nygren@telia.com> wrote in message
news:311c6b78.0409271138.1795d07c@posting.google.com...
>
> after spending numerous hours to do a simple double linked list
> package - yes, I have seen charles - a 5 hours tedious car drive came
> up with the following example of an improved Ada language:
>   - prefix notation (as for tasks and protected types)
>   - Ada OO syntax in line with tasks and protected objects
>   - reference types
>   - controlled, allocates from Storage_Pools.Garbage_Collected :)
>   - implicit up- and down-conversions

Distinguished-receiver syntax is being added to the language, for tagged
types.

  L : List;
begin
  L.Append (42);

This is largely the reason why we made the AI-302 container types publicly
tagged.

Tagged types and limited types are already pass-by-reference, so usually you
don't need explicit reference types (a la C++), since the pass-by-reference
happens automatically.

The fact that the type is publicly tagged means that you're allowed to alias
parameters:

procedure Op (L : in out List) is
begin
   ... L'Access ...; --ok
end;

For class-wide types, the up-conversion happens automatically, since the
ancester class-wide type "covers" its descendent, e.g.

type T is tagged null record;
type NT is new T with null record;

procedure Op (O : T'Class);

declare
   O : NT;
begin
   Op (O);  --ok
end;

All the AI-302 containers (including the list) are controlled, so memory
management ("garbage collection") is automatic.

Not sure what your issue is, I guess...