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From: Matthew Heaney <matthew_heaney@acm.org>
Subject: Re: Can't export object of private type
Date: 1999/03/01
Message-ID: <m3vhgm9b88.fsf@mheaney.ni.net>#1/1
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Sender: matt@mheaney.ni.net
References: <7b8cvc$ii5$3@plug.news.pipex.net> <F7w5zn.G7z@syd.csa.com.au>
NNTP-Posting-Date: Sun, 28 Feb 1999 18:44:55 PDT
Newsgroups: comp.lang.ada
Date: 1999-03-01T00:00:00+00:00
List-Id: <comp.lang.ada>

nospam@thanks.com.au (Don Harrison) writes:

> Nick Roberts wrote:
> 
> :   package Planetary is
>        ...
> :      type Planet_Id is private;
>        ...
> :   private
> :      ...
> :   end Planetary;
> 
> The problem here is that you lose the property of having a single instance:
> 
> >   1) Have only one instance
> 
> Since Planet_Id is exported, anyone can declare an object of that type. 
> We want to ensure there is only a single instance shared by all clients.


Then declare the Plant_Id type as limited and indefinite:

package Planetary is

  type Planet_Id (<>) is limited private;

...
end Planetary;