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From: "Steve" <nospam_steved94@attbi.com>
Newsgroups: comp.lang.ada
Subject: Suggestion for Ada 200x - Interface inheritance
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Xref: archiver1.google.com comp.lang.ada:37723
Date: 2003-05-23T23:05:32+00:00
List-Id: <comp.lang.ada>

Java and C# use the concept of interface inheritance.  What do you think of
adding this feature to Ada?

A tagged type containing only abstract methods (functions and procedures)
would be considered to be an interface.  Any tagged type may be dervied from
at most one tagged type containing data elements and any number of
interfaces.

That is, you may define an interface:

  type interface_example is abstract tagged null record;

  function in_order( obj : interface_example ) return boolean;

  procedure swap( obj1, obj2 : in out interface_example );

  type data_value is tagged
    record
      field1 : Natural;
      field2 : Natural;
    end record;

  type sorted_data is new data_value, interface_example with
    record
      is_valid : Boolean;
    end record;

The objective is to add interfaces to existing objects such that they may be
used by common routines, in the same way as Java.  In fact this might make
it easier to interface with Java.

Steve
(The Duck)