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From: mg@harp.camb.inmet.com (Mitch Gart)
Subject: Re: Converting C++ class to Ada
Date: 1996/12/20
Message-ID: <E2ptyG.GIu.0.-s@inmet.camb.inmet.com>#1/1
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Date: 1996-12-20T00:00:00+00:00
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Jon S Anthony (jsa@alexandria) wrote:

: CE is raised if a null value is passed to an access _parameter_.  
(snip)
: A good thing IMO on both counts.  See in particular 11.5(11)

I think this is a mistake in Ada 95.  Not allowing null for an
access parameter makes it harder to interface to C:

    procedure P(param: access thing);
    pragma import(C, P);

You can't call P(null) even though the C function may have 
semantics defined for null.  You have to make up a named
access type for the parameter.

Users of Win32Ada and X11Ada will notice that the bindings
contain access parameters in many places.  This is a mistake
that needs fixing given the above Ada 95 rule.

- Mitch Gart
- mg@inmet.com