R++: adding path-based rules to C++

Abstract

Object-oriented languages and rule-based languages o er two distinct and useful programming abstractions. However, previous attempts to integrate data-driven rules into object-oriented languages have typically achieved an uneasy union at best. R++ is a new, closer integration of the rule-based and object-oriented paradigms that extends C++ with a single programming construct, the path-based rule, as a new kind of class member. Path-based rules|data-driven rules that are restricted to follow pointers between objects|are like \automatic methods" that are triggered by changes to the objects they monitor. Path-based rules provide a useful level of abstraction that encourage a more declarative style of programming, and are valuable in object-oriented designs as a means of modeling dynamic collections of interdependent objects. Unlike more traditional pattern-matching rules, path-based rules are not at odds with the object-oriented paradigm, and o er performance advantages for many natural applications.

Algorithms for user interfaces

“…The QTk library [12] in Mozart/Oz, Glade [7], XUL [16], XAML [34], and XForms [5] serve as further examples. Some of these systems, along with rule-based systems such as Drools [27], Jess [11], and R++ [14], also support concisely specifying declarative rules for maintaining consistency across values in user interfaces. Property models are distinguished from these systems by not only providing the ability to create rules that assist in producing a valid result but also by providing an explicit model of the dependencies these rules create.…”

Sensor enabled rule based alarm system for the agricultural industry

“…TE uses a modified version of the rule evaluation engine presented in [6]. The engine implements a path based approach in rule evaluation similar to the R++ evaluation logic [7]. TE can processes streams of incoming sensor data and decide whether the testing of the rules should be triggered.…”