Object Oriented Computing

In this contribution, the basic overview of the Object Oriented Programming and its usage in computation is given. Concepts of class, encapsulation, inheritance, and polymorphism are introduced. Some additional concepts like interface and Design Patterns are briefly discussed. Schematic examples in C++ are given. --

Flexible Invariants Through Semantic Collaboration

Modular reasoning about class invariants is challenging in the presence of dependencies among collaborating objects that need to maintain global consistency. This paper presents semantic collaboration: a novel methodology to specify and reason about class invariants of sequential object-oriented programs, which models dependencies between collaborating objects by semantic means. Combined with a simple ownership mechanism and useful default schemes, semantic collaboration achieves the flexibility necessary to reason about complicated inter-object dependencies but requires limited annotation burden when applied to standard specification patterns. The methodology is implemented in AutoProof, our program verifier for the Eiffel programming language (but it is applicable to any language supporting some form of representation invariants). An evaluation on several challenge problems proposed in the literature demonstrates that it can handle a variety of idiomatic collaboration patterns, and is more widely applicable than the existing invariant methodologies.Comment: 22 page

Assessing design patterns for concurrency

Design patterns are language-independent software-engineering techniques for solving recurring problems within a particular problem-context. Despite their generality, they have been primarily adopted by, and for the most part developed within, the object-oriented community. As a result, some pattern definitions are sometimes expressed with objects-oriented machinery in mind such as classes and inheritance. We test the paradigm independence of these design patterns and investigate the viability of adopting existing patterns from the object-oriented paradigm to the message-passing concurrency setting. By porting these techniques to the new programming paradigm, we expect to inherit the benefits associated with these design patterns. We achieve these goals by implementing a suite of design patterns as reusable modules in Erlang, an industry-strength message-passing language for programming concurrent distributed systems.peer-reviewe

An Object-Oriented Framework for Robust Multivariate Analysis

Taking advantage of the S4 class system of the programming environment R, which facilitates the creation and maintenance of reusable and modular components, an object-oriented framework for robust multivariate analysis was developed. The framework resides in the packages robustbase and rrcov and includes an almost complete set of algorithms for computing robust multivariate location and scatter, various robust methods for principal component analysis as well as robust linear and quadratic discriminant analysis. The design of these methods follows common patterns which we call statistical design patterns in analogy to the design patterns widely used in software engineering. The application of the framework to data analysis as well as possible extensions by the development of new methods is demonstrated on examples which themselves are part of the package rrcov.

Software patterns to improve knowledge transfer: an experiment.

Patterns for software development have been a hot topic for some time within the object-oriented community. Patterns are part of a software engineering problem-solving discipline. It all started with Design Patterns [11], but gradually patterns were used in a larger number of areas of system development. The goal of patterns within the software community is to create a body of literature to help software developers resolve recurring problems encountered throughout all areas of software development. Patterns help to create a shared language for communicating insight and experience about these problems and their solutions [4]. In this research report, first, a definition of software patterns is given, including some history, an overview of the different kinds of software patterns, the elements of a pattern and the different pattern formats. Secondly, as patterns claim to improve transfer of knowledge, we performed an experiment to test this hypothesis. This experiment is described in Section 2. Finally, Section 3 formulates the conclusions about this experiment.