Object-oriented Software in Ada 95

Exceptions 181
12.3.5 use type
A modified form of the use clause allows operators from a package to be used without having to prefix the
operator with the package name. Other components however, from the package need to be prefixed with the
package name when used. This modified form of the use clause is use type which is followed by the type name
whose operators can be used without prefixing them by the package name. For example, the following program
requires all components in the package Bounded_String except for operators to be prefixed with the package
name.
with Ada.Text_Io, Class_Bounded_String;
use type Class_Bounded_String.Bounded_String;
procedure Main is
Town : Class_Bounded_String.Bounded_String :=
Class_Bounded_String.To_Bounded_String("Brighton");
County: Class_Bounded_String.Bounded_String :=
Class_Bounded_String.To_Bounded_String("E Sussex");
begin
Ada.Text_Io.Put(
Class_Bounded_String.To_String( Town & " " & County )
);
end Main;
12.4 Self-assessment
• What operators can be overloaded with a new meaning in Ada?
• Can a user invent new operators? For example, could a user define the monadic operator ++ to add
one to an integer?
• Why might excessive use of overloading the standard operators lead to a program that is difficult to
follow?
• Why is the function rat_const needed in the class Rational?
• How can a user guarantee to use the definition for the operator + in the package standard?
12.5 Exercises
Construct the following class:
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