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From: robert_dewar@my-dejanews.com
Subject: Re: How do I get this to work??
Date: 1999/01/19
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Date: 1999-01-19T00:00:00+00:00
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In article <naRo2.8635$Kg6.64266@news2.telusplanet.net>,
  warwicks@telusplanet.net (Chris Warwick) wrote:

> Of the Ada compilers I have used, the
> unchecked_deallocation on all of them
> was to set the pointer to 0 and carry on (i.e., no calls
> to deallocate, no
> storing the un-used memory for later re-allocation by the
> Ada program). When I
> first stumbled into this I was told that this was for
> safety reasons. It may
> have been that I have been using safety critical versions
> of these Ada
> compilers, and "standard" compilers are different...
>

I have already discussed this with Chris. He claimed that
VADS behaved as above, which I know to be incorrect, and
he claimed that Alsys behaved as above. I particularly know
the latter claim to be false, since I wrote that code! The
one thing in Alsys that he may be referring to was that for
certain cases of small blocks in local collections, we
deferred collecting the storage till scope exit, but that
is the only case where there was even a deferral of the
free operation.

The claim that this has to do with safety is just wrong.

And as for safety critical subsets, clearly these do not
even allow Unchecked_Deallocation in the first place.

Clearly Chris's statements here are based on
misinformation, or misinterpretation of some kind,
and it is important not to be mislead by them.

Unchecked_Deallocation works just fine on all Ada compilers
and always has, it is as reliable as free in C (and indeed
on many compilers translates directly into a free call).

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