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From: mheaney@on2.com (Matthew Heaney)
Newsgroups: comp.lang.ada
Subject: Re: "access constant" discriminant
Date: 21 Feb 2003 13:33:43 -0800
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Hyman Rosen <hyrosen@mail.com> wrote in message news:<1045839826.87966@master.nyc.kbcfp.com>...
> Matthew Heaney wrote:
> > Access parameters carry accessibility information around, to check
> > that an object in an outer scope doesn't refer to another object in an
> > inner scope.
> 
> Do they actually carry this information around?
> I thought that the language rules just prevented
> such "inner" addresses from winding up in an
> "outer" pointer, not that the pointers themselves
> were "fat".

Access parameters carry accessibilty information around (not all
checks can be done statically).

Note that named access types do *not* carry the same information.  

When an access check fails at run-time, it's often because you're
assigning the value of an access parameter to an access object. 
That's why you sometimes have to do the assignment using
'Unchecked_Access instead.