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Virtual Object

IP.com Disclosure Number: IPCOM000105374D
Original Publication Date: 1993-Jul-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 4 page(s) / 122K

Publishing Venue

IBM

Related People

Campbell, DL: AUTHOR [+4]

Abstract

Disclosed is the programming concept of a virtual object, which is an approach for resolving object references in an object oriented system. References which specify objects that do not exist in the object space of the OO system, are resolved by computation. The computation consists of two parts,

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Virtual Object

Disclosed is the programming concept of a virtual object, which is an
approach for resolving object references in an object oriented
system.  References which specify objects that do not exist in the
object space of the OO system, are resolved by computation.  The
computation consists of two parts,

1.  Computation of the object's inheritance class.
2.  Computation of the object's address in the OO system.

      Current object oriented systems -- from programming languages
to databases -- require that all objects be predefined to the system
before access can occur.  This is accomplished by defining the object
name and its associated inheritance class along with any
instance-specific descriptive attributes.  Once the formalities of
definition have been satisfied, the OO system is free to reference
the object as required.  If a reference is made to an object that
does not exist in the system's object space, an error condition
results.

      Using this approach, object classes are static.  They cannot be
dynamically determined by the execution environment or according to a
defined rule set.  This necessitates the use of object's methods --
the actions which operate on the object -- to behave according to
environ- mental conditions, since the object's data cannot.

      An example of this approach is the make program compilation
tool.  Although make is not an object-oriented system per se, its
definition syntax and operation semantics are consonant with object
orientation:

o   The make description file is the formal definition of all objects
    known to the system.
o   Each entry, or object, in the description file has a dependency
    line which describes relationships to other objects.
o   Each object also has one or more command lines which specify
    instance-specific methods to execute.
o   The class of an object is determined using suffix rules that
    operate on the object's name.  For instance, objects with a name
    ending with the string ".o" are of the "object code" class.

      The description file defines all of make's object space.
References to objects not found in the description file result in an
error.  Make objects are statically bound to a particular inheritance
class according to their names.  Computation of an object class based
on operating environment or user-specified rules is not allowed.
Therefore, make is unable to handle object relationships other than
those defined by its dependency rules and is also poorly suited to
accommodating object classes other than program compilation files.

           All other known object oriented systems exhibit similar
limitations.

      To overcome the limitations imposed by object predefinition,
this disclosure proposes the concept of the "Virtual Object."  Within
this concept, a method is defined global to the OO system, which
computes the inheritance class(es) of objects that do not exist in
the...