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From: Stephen Leake <Stephen.Leake@gsfc.nasa.gov>
Subject: Re: question about functions
Date: 2000/01/24
Message-ID: <uwvozl2hp.fsf@gsfc.nasa.gov>#1/1
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Date: 2000-01-24T19:03:25+00:00
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"Matthew Heaney" <matthew_heaney@acm.org> writes:

> In article <un1q01s1n.fsf@gsfc.nasa.gov> , Stephen Leake 
> <Stephen.Leake@gsfc.nasa.gov>  wrote:
> 
> > One alternate approach that is possible in Ada is to pass the result
> > as an 'out' parameter :
> >
> > procedure f (A, B : in T; C : out T);
> >
> > now you can do C'Address.
> 
> C'Address is only defined if T is a by-reference type.
> 
> See RM95 13.3 (16).

13.3 (16) is implementation advice; it suggests that X'Address be
   useful in certain situations, including by-reference types.

X'Address is _defined_ in 13.3 (11), which says nothing about where it
may be useful. Hmm, I'm not clear if a subprogram parameter is an
"object" here, but I believe it is.

In any case, I have often successfully used 'Address on subprogram
parameters that are not of a by-reference type, with both ObjectAda
and GNAT, so at least some compilers go beyond the implementation advice.

-- Stephe