Object-oriented Software in Ada 95

Packages as classes 85
which when run, will produce:
Mini statement: Account £ 10001
The amount on deposit is £200.00
Mini statement: Account £ 10002
The amount on deposit is £200.00
6.10.2 Restrictions
The following restrictions apply, however:
• Only discrete objects or access values may be used as the discriminant value. If an access value is used
then the type must be limited.
• To change the discriminant value the whole record structure must be changed.
Thus the implementation of the procedure New_Number that allocates a new account number is:
procedure New_Number( The: in out Account; N:in Natural ) is
begin
The := Account'( N, The.Balance_Of );
end New_Number;
Note:
The whole record structure needs to be changed to change the discriminant. Chapter 7 discusses
record initialization in more detail.
6.10.3 By assignment
In this case the object is assigned an initial value when it is declared. For example, the following code sets
My_Account with an account number and initial balance:
with Class_Account, Statement;
use Class_Account;
procedure Main is
My_Account : Account := New_Account( 10001, 20.0 );
begin
Statement( My_Account );
end Mai3;
which when run, will produce:
Mini statement: Account £ 10001
The amount on deposit is £20.00
© M A Smith - May not be reproduced without permission