Re: Flags in Ada?

[spiegel@bruessel.informatik.uni-stuttgart.de (Andre Spiegel)]

[referring to Norman H. Cohen's article <38jb6s$tsr@watnews1.watson.ibm.com>]

Thanks for the flag example. I had missed the section in the RM which
says that boolean operators can also be applied to boolean arrays. 
I suppose that compilers also recognize that what I want is bit
arithmetic, and therefore won't generate loops to apply the operator
to the arrays elementwise, which would of course be ridiculously slow.

Thanks also for the explanations on address clauses. This is the way
in which I have been doing it in my program, too. I was just wondering
about efficiency, because those `declare' statements "look" somewhat
expensive. For example, if UNIX fills a buffer with data items of
varying length (talking about ethernet packets, actually), and I want
to scan that buffer in an Ada loop, there has to be a declare
statement *within* the loop, in order to, sort of, "move" the record
pattern over the buffer.  

This seems a little counter-intuitive, because it's so different from
what you would do in C, for example -- simply declare a pointer to a
struct, and increment that pointer accordingly. I have found,
meanwhile, that in Ada 9X the generic package Interfaces.C.Pointers
will provide precisely that. But from what you wrote, I conclude that
the declare statement solution does not translate into anything
different at the machine level. It probably even looks more Ada-like.

--
Andre Spiegel                     |  This life is a test. It is only a test.
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