Re: Mission-Critical Design: Ada.Unchecked_Deallocation vs Garbage Collection

[Robert A Duff <bobduff@shell01.TheWorld.com>]

Dennis Lee Bieber <wlfraed@ix.netcom.com> writes:

> On Thu, 17 Jul 2014 23:17:48 -0700 (PDT), NiGHTS <nights@unku.us> declaimed
> the following:
>
>>In mission-critical design applications, do they favor garbage collectors or the unchecked deallocation?
>>
> 	Based upon the examples I've seen at work (flight management systems):
> NEITHER...
>
> 	Any dynamic memory gets allocated during the initialization step (based
> on some configuration "file" to identify how much of each component to
> create), and once that completes the only "dynamic" memory is the stack
> (and not even the secondary stack used in some operations -- like run-time
> string concatenation; no: put("string " & integer'image(val) & " more"); )

That particular example can be done without using the secondary stack in
the latest version of GNAT.  All the temps are allocated on the primary
stack, with compile-time-known size.  The length of X&Y is equal to the
sum of the lengths of X and Y.  The maximum length of the 'Image result is 11.

Take a look at the output of -gnatD if you want to see how that works.

- Bob