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From: Christoph Grein <christoph.grein@eurocopter.com>
Newsgroups: comp.lang.ada
Subject: Re: Help: Type not accessible
Date: Tue, 19 Mar 2002 15:45:13 +0100 (MET)
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Date: 2002-03-19T15:45:13+01:00

> procedure Main is
> 
>     Mynav : aliased Nav;
> 
>     Pointer_To_Nav : Navpointer;
> 
>  begin
> 
>     --create a pointer to the nav to give to the nav interface
>     Pointer_To_Nav := Mynav'Access;  <--- THIS LINE WILL NOT COMPILE
> 
> 
> It tells me that 'Mynav is not accessible from  access all nav'.
> Can someone please help. I have no idea what to do here, or what is causing
> it.


You've fallen victim to the accessibility level problem. Your Navpointer has a 
longer lifetime than your variable Mynav. You could copy Pointer_To_Nav to 
another pointer with longer lifetime than Main, i.e. it would point to an object 
that no longer exists.

That you don't do this here is irrelevant, what matters is lifetime or in RM 
speak accessibility levels.

Use 'Unchecked_Access instead, and you're on yourself to prevent dangling 
pointers.