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From: "REH" <spamjunk@stny.rr.com>
Newsgroups: comp.lang.ada
Subject: Re: aliased and parameters
Date: 31 Jul 2006 12:02:45 -0700
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Date: 2006-07-31T12:02:45-07:00
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Jeffrey R. Carter wrote:
> REH wrote:
> > ...
> > recv(socket, Hdr'Address, header_size);
> >
> > The problem is that some Ada95 compiler are so aggressive with
> > optimization that they may not "see" then Hdr is changed by recv.  At
> > the very less the compiler complains (rightfully so) that Hdr is alised
> > but not marked as such.  But how do enforce that if I cannot define the
> > parameter as aliased?  Should I use an access type instead and convert
> > it to System.Address, or is there a cleaner way?
>
> You should not be using 'Address at all. I don't know the definition of
> Recv, so I can't say what would be better. If it's an interface to C,
> you might want an array or a C-compatible access value.
>
> Of course, that assumes you can change the library in question.
>
> --
> Jeff Carter
> "Death awaits you all, with nasty, big, pointy teeth!"
> Monty Python & the Holy Grail
> 20

Thanks Jeff.  recv is the standard POSIX (or BSD) socket receive
function.  It takes a pointer.  Yes, I could use an array (as I could
still map it to a C pointer).  The problem with this is I either have
to move the data from its "normal" type into the array (excessive data
movement) or I have to map the array over top of my data (which gets us
right back to using 'Address).

REH