Object-oriented Software in Ada 95

224 Polymorphism
15.6.1 Putting it all together
Using the above declarations the following program can be written:
with Ada.Text_Io, Ada.Float_Text_Io;
use Ada.Text_Io, Ada.Float_Text_Io;
procedure Main is
type P_Fun is access function(Item:in Float) return Float;
type Vector is array ( Integer range ) of Float;
-- Body of the procedures apply, square and float
procedure Put( Items:in Vector ) is
begin
for I in Items'Range loop
Put( Items(I), Fore=>4, Exp=>0, Aft=>2 ); Put(" ");
end loop;
end Put;
begin
Numbers := (1.0, 2.0, 3.0, 4.0, 5.0);
Put("Square list :");
Apply( Square'access, Numbers );
Put( Numbers ); New_Line;
Numbers := (1.0, 2.0, 3.0, 4.0, 5.0);
Put("cube list :");
Apply( Cube'access, Numbers );
Put( Numbers ); New_Line;
end Ex2;
which when run, will produce the following results:
Square list : 1.00 4.00 9.00 16.00 25.00
cube list : 1.00 8.00 27.00 64.00 125.00
Note:
A program is not allowed to take the address of a predefined operator such as Standard."+". This
is to ease compiler implementation.
© M A Smith - May not be reproduced without permission