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From: nasser@apldbio.com
Subject: Re: Static variables?
Date: 1997/03/18
Message-ID: <5go0s7$2un@lana.zippo.com>#1/1
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References: <332D71FF.4773@cae.ca> <dewar.858642450@merv>
Organization: Perkin-ELmer
Newsgroups: comp.lang.ada
Date: 1997-03-18T00:00:00+00:00
List-Id: <comp.lang.ada>


as Dr Dewar mentioned, package variables retain their values
from the time the package becomes avaliable to the time the
package life ends (usually the end of the program , but not
always the case, example, if the package is declared inside
a block or procedure), may be a picture will help:
 
 
 
                   package A interface
                 +---------------------+
                 | i: integer;   -----------> retain its value also
client <=======> | procedure foo;      |
                 | .......             |
                 +---------------------+               
          
         .............................................
       
                   package A body
                 +---------------------+
                 |j: integer;   --------------> these variables retain
                 |                     |         their values 
                 | procedure foo is    | 
                 |   n: integer;  ------------> variables here are auto
                 |   begin             |        variables, new copies are
                 |     ....            |        created each time foo is called
                 | end foo;            |
                 |                     |
                 | begin               |
                 |   ....    ----------------> this code execute once when
                 | end A;              |       package is first elaborated. 
                 |                     |       use this code to init package
                 +---------------------+       variables.
                                               
 
you can think of variables declared in the package interface as static puplic
in C++ class terminolgy, and variables declared in the body of the package 
but outside the functions and procedure of the package body as static 
private in C++.
 
offcourse it is a good idea to try to avoid using variables in the interface
part of the package.
 
nasser