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Fast Method for Enabling Secondary Inheritance

IP.com Disclosure Number: IPCOM000105977D
Original Publication Date: 1993-Sep-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 83K

Publishing Venue

IBM

Related People

Calo, SB: AUTHOR [+2]

Abstract

Disclosed is a scheme for resolving constraints on secondary inheritance relationships when object classes are defined, and for maintaining sufficient information to allow minimal checking at invocation.

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

Fast Method for Enabling Secondary Inheritance

      Disclosed is a scheme for resolving constraints on secondary
inheritance relationships when object classes are defined, and for
maintaining sufficient information to allow minimal checking at
invocation.

      The proposed scheme incorporates information regarding
inheritance mechanisms into the object definitions in order to
provide good run-time performance.  In particular, information about
potential inheritance relationships is collected at the time object
classes are defined; consistency checking is performed at definition
time; and minimal overhead is incurred at the time the secondary
inheritance relationship between class instances is actually
established.

      Assume a basic object model in which objects are organized into
classes and the structure of an object is determined by the structure
of its parent class.  Classes in turn also have parent classes
(called superclasses) and are arranged in a tree-structured
taxonomical hierarchy (called the primary hierarchy) that supports
default value inheritance as well as structural inheritance.  In
addition, the fields that hold the attribute values within an object
are organized into trees.  Groups of fields are associated with
substructures that are in turn associated with other fields and
substructures in an hierarchical arrangement.  One of the fields that
is required to be in every object holds the identity of its primary
parent and is directly associated with the object itself (the root of
the substructure hierarchy).

      The substructures designated within the object are used for
directing value inheritance.  Each substructure contains information
regarding whether primary or secondary inheritance should be used in
resolving the values of any of the fields associated with it, and in
the latter case, which field within the object to use to identify the
secondary parent and the particular substructure within that parent
to be employed.  These child of fields, in conjunction with the
parent of fields in the associated (parent) object, capture the
specific linkage information.  The indirection incorporated in the
specification of the secondary relationship is useful in supporting
dynamic changes.

      In order to avoid long primary inh...