Object-oriented Software in Ada 95

192 Child libraries
Another generic procedure G_3Order can be written which will order its three parameters. This new procedure
uses an instantiation of the procedure G_Order internally.
generic
--Specification
type T is ( ); --Any discrete type
procedure G_3Order( A,B,C:in out T ); --Prototype ord
with G_Order;
procedure G_3Order( A,B,C:in out T ) is --Implementation ord
procedure Order is new G_Order( T ); --Instantiate order
begin
Order( A, B ); --S L -
Order( B, C );
--? ? L
Order( A, B );
--S M L
end G_3Order; --
Note:
The generic parameter T can only be a member of the discrete types. This is achieved with the
declaration of the type T as ‘type T is ()’.
The procedure order in the procedure G_3Order is an instantiation of the generic procedure
G_Order with an actual parameter of type T.
Figure 14.1 illustrates the components of a generic procedure.
Specification of
generic procedure
Generic
type T is ( );
The formal type specifies the
category of types to which the
generic parameter can belong
procedure G_Order( A,B:in out T );
Implementation of
generic procedure
procedure G_Order( A,B:in out T ) is
Tmp : T;
begin
-- Code of generic procedure
end G_Order;
Figure 14.1 Components of a generic procedure declaration.
© M A Smith - May not be reproduced without permission