Object-oriented Software in Ada 95

Inheritance 151
The two classes Account and Interest_Account can be used in a program to perform some simple bank
transactions. A program to illustrate the use of the new class Interest_Account and the original class
Account is shown below:
with Ada.Text_io,
Class_Interest_Account, Class_Account, Statement;
use Ada.Text_io,
Class_Interest_Account, Class_Account;
procedure Main is
Mike :Account; --Normal Account
Corinna :Interest_Account; --Interest bering account
Obtained:Money;
begin
Set_Rate( 0.00026116 );
Statement( Mike );
--For all instances of
--interest bering accounts
Put("Deposit £50.00 into Mike's account"); New_Line;
Deposit( Mike, 50.00 );
Statement( Mike );
Put("Withdraw £80.00 from Mike's account"); New_Line;
Withdraw( Mike, 80.00, Obtained );
Statement( Mike );
Put("Deposit £500.00 into Corinna's account"); New_Line;
Deposit( Corinna, 500.00 );
Statement( Account(Corinna) );
Put("Add interest to Corinna's account"); New_Line;
Calc_Interest( Corinna );
Add_Interest( Corinna );
Statement( Account(Corinna) );
end Main;
In this program, the procedure Statement takes as its parameter an instance of an Account. However, as
the account for Corinna is an instance of a Interest_Account it must first be converted to an instance of an
Account before it can be passed as an actual parameter to Statement. This is accomplished with a view
conversion Account(Corinna). The actual parameter passed to Statement is now viewed as if it were an
Account.
which, when compiled and run, would produce the following output:
Mini statement: The amount on deposit is £ 0.00
Deposit £50.00 into Mike's account
Mini statement: The amount on deposit is £50.00
Withdraw £80.00 from Mike's account
Mini statement: The amount on deposit is £50.00
Deposit £500.00 into Corinna's account
Mini statement: The amount on deposit is £500.00
Add interest to Corinna's account
Mini statement: The amount on deposit is £500.13
© M A Smith - May not be reproduced without permission