Re: Limited use for limited with?

["Martin Krischik" <krischik@users.sourceforge.net>]

Am 08.10.2010, 02:07 Uhr, schrieb Randy Brukardt <randy@rrsoftware.com>:

> "Martin Krischik" <krischik@users.sourceforge.net> wrote in message
> news:op.vj7xjle3z25lew@macpro-eth1.krischik.com...
> ...
>>> Inside Foo_Two, we know that the accessibility level of A is the same  
>>> as
>>> the declaration of My_Access_Type,
>>
>> Are you realy sure about that? My_Access_Type is an access *all* and  
>> could
>> point to an aliased value on the stack.
>
> He is. If you try to store an access to an aliased value on the stack  
> into
> My_Access_Type, you'll get a compile-time error that the accessibility
> fails. (Or, in a few obscure cases, Program_Error will be raised.) The  
> rules
> that guarentee this are a constant source of headaches for the ARG and
> implementers, but Ada users don't need to worry about that.

But if you mention Program_Error then the accessibility can not be checked  
at compile time in all circumstances. In which case an access all is not  
at all better then an anonymous access. Only a plain access will guarantee  
that accessibility can be checked statically in all circumstances.

Regards.

Martin
-- 
Martin Krischik
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https://sourceforge.net/users/krischik