TI The Constraint-Based Paradigm: The Integration of the
Object-Oriented and Rule-Based Programming Paradigms 

LT CUCS-009-90 

OR COLUM 

YR 1990 

TR Ph.D. Dissertation 

AU Michael van Biema 

AB This thesis introduces a new formalism, {\em Constraint-Based
invocation}, that combines the Object-Oriented and Rule-Based
paradigms in an elegant and orthogonal way.  The Constraint-Based
model is a generalization of traditional method invocation in
Object-Oriented programming that allows method discrimination on
the basis of arbitrary user-defined predicates.  Languages based
on the Object-Oriented and Rule-Based paradigms have both been in
existence for some time.  Yet both paradigms suffer from a few
lingering problems that have been well identified in the
literature.  Constraint-Based invocation provides solutions for
such problems as multiple inheritance in Object-Oriented systems
and the expression of control in Rule-Based systems by uniting
them in terms of constrained method invocation.  The single
underlying representation of both rules and methods allows the
expression of their resolution in terms of meta-methods.  This
thesis also introduces the concept of {\em instance inheritance}
into ObjecOriented systems.  In instance inheritance a {\em
collection} represents the dual of the concept of a class in the
traditional structural inheritance of current Object-Oriented
languages.  Collections allow the grouping of both objects and
methods and since by definition methods are applied to
collections in parallel, collections form the basis for the
expression of both data and control parallelism under the
Constraint-Based model. The thesis concludes with a discussion of
how the introduction of these two concepts leads to an increase
in the ease of expression and implementation of parallelism in
both Object-Oriented and Rule-Based systems.  An additional
central philosophical argument of the thesis is that so called
`multi-paradigm' languages should be developed not by combining
paradigms into a partially integrated system, but rather by their
unification into a synergistic language developed under a new,
subsuming paradigm.