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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Legit Warnings or not
Date: Fri, 22 Jul 2011 19:52:13 -0500
Organization: Jacob Sparre Andersen Research & Innovation
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Date: 2011-07-22T19:52:13-05:00
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"Robert A Duff" <bobduff@shell01.TheWorld.com> wrote in message 
news:wcc8vrrbrb6.fsf@shell01.TheWorld.com...
...
> Implicit heap allocation could be a good feature in a different
> language, but then I'd want that language to allow:
>
>    type Tree is tagged
>        record
>            Left, Right : Tree'Class; -- doubly illegal!
>        end record;

Yes, of course Ada should support this, too. ;-) As noted, it's not 
particularly hard.

Note that these sorts of allocations aren't really the same as heap 
allocations -- their lifetime is similar to that of the secondary stack. 
Janus/Ada does allocate them on the heap (with them being deallocated when 
scope goes away), but I've been thinking about ways to reduce/eliminate 
that. One obvious idea is to allocate the initial sizes off of the secondary 
stack, and only allocate from the heap if they get bigger via assignment in 
a different master (which is fairly rare). Not sure if that would save 
enough to be worth the extra complication.

                                     Randy.