Object-oriented Software in Ada 95

158 Inheritance
with Ada.Text_Io, Ada.Float_Text_Io;
use Ada.Text_Io, Ada.Float_Text_Io;
package body Class_Named_Account is
procedure Set( The:out Named_Account; Str:in String ) is
begin
Set( The.Naa, Str );
end Set;
function Deliver_Line( The:in Named_Account;
Line:in Positive ) return String is
begin
return Deliver_Line( The.Naa, Line );
end Deliver_Line;
function Lines( The:in Named_Account ) return Positive is
begin
return Lines( The.Naa );
end Lines;
The implementation of the methods in Named_Account which are inherited from Account are as follows:
procedure Deposit(The:in out Named_Account; Amount:in Pmoney) is
begin
Deposit( The.Acc, Amount );
end Deposit;
procedure Withdraw( The:in out Named_Account; Amount:in Pmoney;
Get:out Pmoney ) is
begin
Withdraw( The.Acc, Amount, Get );
end Withdraw;
function Balance ( The:in Named_Account ) return Pmoney is
begin
return Balance( The.Acc );
end Balance;
end Class_Named_Account;
A procedure Statement to print a mini statement of the state of an instance of a Named_Account is defined
as follows:
with Ada.Text_Io, Ada.Float_Text_Io, Class_Named_Account;
use Ada.Text_Io, Ada.Float_Text_Io, Class_Named_Account;
procedure Statement( An_Account:in Named_Account ) is
begin
Put("Statement for : " ); Put( Deliver_Line(An_Account, 1)); New_Line;
Put("Mini statement: The amount on deposit is £" );
Put( Balance( An_Account), Aft=>2, Exp=>0 );
New_Line(2);
end Statement;
Note: Again by not permiting an input or output operations to be part of the class, the scope for its potential
re-use is increased.
© M A Smith - May not be reproduced without permission