Object-oriented Software in Ada 95

Preface
xvii
Class attribute
A data component that is shared between all objects in the class. In effect it is
a global variable which can only be accessed by methods in the class. A class
attribute is declared in the private part of the package representing the class.
For example, the class attribute The_Interest_Rate in the class
Interest_Account is declared in the private part of the package as
follows:
package Class_Interest_Account is
type Interest_Account is private;
procedure Set_Rate( Rate:in Float );
private
type Interest_Account is new Account with record
Balance_Of : Money := 0.00;
Accumulated_Interest : Money := 0.00;
end record;
The_Interest_Rate : Float := 0.00026116;
end Class_Interest_Account;
Class method
A procedure or function in a class that only accesses class attributes. For
example, the method Set_Rate in the class Interest_Account which
sets the class attribute The_Interest_Rate is as follows:
procedure Set_Rate( Rate:in Float ) is
begin
The_Interest_Rate := Rate;
end Set_Rate;
Note: As Set_Rate is a class method an instance of the class is not
passed to the procedure.
Controlled
object
Discriminant
An object which has initialization, finalization and adjust actions defined. A
limited controlled object only has initialization and finalization defined as
assignment is prohibited.
The declaration of an object may be parameterized with a value. The value is
a discriminant to the type. For example, the declaration of corinna is
parameterized with the length of her name.
type Person( Chs:Str_Range := 0 ) is record
Name : String( 1 .. Chs );
Height : Height_Cm := 0;
Sex : Gender;
end record;
Corinna : Person(7);
Dynamicbinding
The binding between an object and the message that is sent to it is not known
at compile-time.
© M A Smith - May not be reproduced without permission