Re: Generic Packages

[Samuel Tardieu <sam@inf.enst.fr>]

>>>>> "John" == John Herro <johnherro@aol.com> writes:

John> generic formal parameter is treated as a constant in any
John> case. For this reason you can't declare
John> generic
John>   Number : constant Integer;
John> package P is ...

Mmm... I think you are wrong. The reason which prevents you from
modifying Number in your first example is that the "in" keyword is
ommitted. A generic formal may be either "in" or "in out" (of course,
not "out" only).

So you may do:

generic
  Number : in out Integer;
package G is
  procedure Increment;
end G;
package body G is
  procedure Increment is
  begin
     Number := Number + 1;
  end Increment;
end G;

with G;
with Text_IO; use Text_IO;
procedure T is
  I : Integer := 5;
  package P is new G (I);
begin
  Put_Line (Integer'Image(I));
  P.Increment;
  Put_Line (Integer'Image(I));
end T;

and it will print:

5
6

  Sam
--
"La cervelle des petits enfants, ca doit avoir comme un petit gout de noisette"
                                                       Charles Baudelaire