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From: dewar@merv.cs.nyu.edu (Robert Dewar)
Subject: Re: Global Varibles!!
Date: 1997/02/23
Message-ID: <dewar.856748645@merv>#1/1
X-Deja-AN: 220963554
References: <330B6914.22CD@hotmail.com>
 <mheaney-ya023680002002970056270001@news.ni.net>
 <330DD315.6562@watson.ibm.com>
Organization: New York University
Newsgroups: comp.lang.ada
Date: 1997-02-23T00:00:00+00:00
List-Id: <comp.lang.ada>


Norman said

<< package Serial_Numbers is
   procedure Get_Next (Number: out Natural);
end Serial_Numbers;

package body Serial_Numbers is
   Next: Natural := 0:
   procedure Get_Next (Number: out Natural) is
   begin
      Number := Next;
      if Number = Natural'Last then
         Number := 0;
      else
         Number := Number + 1;
      end if;
   end Get_Next;
end Serial_Numbers;
>>

Of course in general this kind of hiding is quite appropriate. Note however
a danger, here we have an unexposed global variable that is not protected
against task switches. If the global is in the spec, you are at least
clearly publishing a warning that you have an unprotected global.