Bridging the gap between design and implementation of components libraries

Object-oriented design is usually driven by three main reusability principles: step-by-step design, design for reuse and design with reuse. However, these principles are just partially applied to the subsequent object-oriented implementation, often due to efficienc y constraints, yielding to a gap between design and implementation. In this paper we provide a solution for bridging this gap for a concrete framework, the one of designing and implementing container-like component libraries, such as STL, Booc h Components, etc. Our approach is based on a new design pattern together with its corresponding implementation. The proposal enhances the same principles that drive the design process: step-by--step implementation (adding just what is needed in every step), implementation with reuse (component implementations are reused while library implementation progresses and component hierarchies grow) and implementation for reuse (intermediate component implementations can be reused in many different points o f the hierarchy). We use our approach in two different manners: for building a brand-new container-like component library, and for reengineering an existing one, Booch Components in Ada95.Postprint (published version

Improving design and implementation of OO container-like component libraries

Object-oriented design is usually driven by three main reusability principles: step-by-step design, design for reuse and design with reuse. However, these principles tend to be just partially applied to the subsequent object-oriented implementation, often because they conflict with other quality criteria (remarkably, efficiency). So, there is a gap between design and implementation: due to these conflicts developers use to give up design level abstractions during the implementation. In this paper we present a framework for bridging this gap for a concrete domain, the design and implementation of object-oriented container-like component libraries, such as JCF, STL, Booch Components, LEDA, etc. At the core of the framework we propose a new design pattern called emph{Shortcut} together with its corresponding implementation. The Shortcut pattern, introduced in a generic base class container, provides a secure and efficient access to items in a container decoupled from the implementation details of concrete containers. Shortcut enhances applying the same principles that drive the design process to the implementation process of these libraries: step-by-step implementation, implementation with reuse and implementation for reuse without penalising other quality criteria. Our framework not only supports the design and implementation of new libraries but also the reengineering of existing ones to overcome some of their drawbacks. We show by a case study, reengineering the Booch Components in Ada95, the application and benefits of our framework.Postprint (published version

Adding efficient and reliable access paths to the JCF

The Java Collections Framework (JCF) is the standard Java library for representing and manipulating collections (i.e., objects that represent a group of objects, such as sets, lists, etc.). Although JCF provides adequate functionality for many purposes, it does not offer any mechanism for accessing directly the objects stored in collections apart from the standard Java references. This absence is a crucial functionality exhibited by many other widespread Java and non-Java collection libraries. In this paper, we carry out a reengineering process on the JCF to add this kind of alternative access paths, which we give the name of shortcuts. This process relies on a framework called Shortcut-Based Framework, which has been defined as library- independent. We present this framework and then we show how it may be tailored to the specific case of the JCF. The resulting JCF with shortcuts library is fully compatible with the original one (i.e., programs using the original JCF are not required to be modified), and exhibits good behaviour with respect to efficiency, reliability and internal quality. As an additional benefit of the framework, we mention that it can be applied to other collection libraries, as we have done before with an Ada95 one.Postprint (published version

Shortcuts: abstract "pointers''

In this work we present the specification and the implementation of a new abstract data type (ADT) called STORE. This new ADT allows the storage of a given collection of elements offering an abstract mechanism that supplies a direct access to them, alternative to the method defined by the standard operations of usual ADTs. The interest of the new mechanism stems from the efficiency of pointers, while avoiding the loss of modularity that usually occurs when pointers are used. The implementation of the operations offered by the new ADT is done by derivation from the equational specification. The representation chosen for the implementation of the new ADT makes the efficiency previously mentioned possible, even when the representation strategy requires the movement of the elements.Postprint (published version

A New Approach for Bounding Awards in Bankruptcy Problems

The solution for the "Contested Garment Problem" proposed in the BabylonicTalmud, one of the most important sources of inspiration for solving situations where demand overcomes supply of some resources, suggests that each agent should receive at least some part of the available amount when facing these situations. Thisidea has been underlied the theoretical analysis of bankruptcy problems from its beginning (O'Neill, 1982) to present day (Dominguez and Thomsom, 2006). In this context, starting from the fact that a society establishes its own set of "Commonly Accepted Equity Principles", we propose a new award bound by providing each agent her minimum amount according to all the admissible bankruptcy rules for such a society. Moreover, we analyze the recursive application of this new bound, since it will not exhaust the resources, in general.Bankruptcy problems, bankruptcy rules, lower bound, recursive process.

Approach to the Neanderthal technical behaviour through the study of lithic assemblages ascribed to the Middle Palaeolithic in Gibraltar

Este trabajo presenta el estudio tecnológico de los conjuntos líticos de los yacimientos adscritos al Paleolítico Medio de Gibraltar: Devil ́s Tower, Ibex Cave, Vanguard Cave, Gorham ́s Cave, Beefsteak y Europe I. Los resultados nos muestran una variabilidad técnica en cada uno de los yacimientos y a su vez una continuidad tecnológica en Gibraltar desde el MIS 5 al 3.This work presents the technological study of the lithic assemblages associate to the Middle Palaeolithic sites from Gibraltar: Devil ́s Tower, Ibex Cave, Vanguard Cave, Gorham ́s Cave, Beefsteak y Europe I. The results show a technical variability in each site and at the same time a technological continuity in Gibraltar since the MIS 5 to 3

Desarrollo de material educativo reutilizable para el portal educativo de la UCM "Acepta el reto"

El juez en línea https://www.aceptaelreto.com desarrollado por profesores de la UCM basa su éxito no solamente en la funcionalidad como juez, sino en la batería de problemas de programación que aloja y que presentan retos lo suficientemente variados como para satisfacer a un amplio rango de usuarios. El documento es la memoria final de un Proyecto de Innovación y Mejora de la Calidad Docente (PIMCD) de 2015 en el que se crearon más de 60 problemas para este juez

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