Browse Prior Art Database

Link Class Hierarchy Design

IP.com Disclosure Number: IPCOM000107315D
Original Publication Date: 1992-Feb-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 72K

Publishing Venue

IBM

Related People

Baber, RL: AUTHOR [+2]

Abstract

The introduction of object-oriented technology into the world of computer programming requires that standard sets of classes be developed for every different type of application. This article describes the design of a class hierarchy for introducing hypertext links into an object-oriented environment.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Link Class Hierarchy Design

       The introduction of object-oriented technology into the
world of computer programming requires that standard sets of classes
be developed for every different type of application. This article
describes the design of a class hierarchy for introducing hypertext
links into an object-oriented environment.

      Provided is a class hierarchy of objects which will maximize
code reuse and allow considerable flexibility in developing
applications utilizing hypertext links. The classes for links are
part of an object-oriented class hierarchy for OfficeVision* which
provides direct manipulation capability of objects via their
representation on a computer screen. For example, a link marker can
be deleted by the end user 'picking the marker up' with a 'mouse
button down' and then dragging the marker to the shredder by moving
the mouse until the marker's image is superimposed on the shredder's
image. When the user 'lets go' of the marker by letting the button up
on the mouse, the delete action is activated.

      The link class hierarchy overcomes the current difficulties in
application development using links by encapsulating the behaviors of
the link objects within individual classes so that each class is
responsible for its own methods. In this way, the design of links can
be upgraded a) by subclassing the current design objects and
overriding the inherited behavior or b) or by developing additional
classes with the new functions.

      The proposed class hierarchy consists of three categories of
objects. Classes are divided into 'model' objects, and 'view' objects
as in the Model-View-Controller scheme used by Smalltalk-80
(ParkPlace Systems). In addition to these, 'database' (persistent)
objects have been added.

      The model objects ...