Position Papers from the 8th Workshop for PhD Students in Object-Oriented Systems

This book contains the position papers accepted at the workshop which took place July 20-21, 1998, in Brussels, Belgium in connection with the ECOOP'98 Conference. The individual papers can be found at http://www.daimi.au.dk/~eernst/ws98/index_details.htm

Type-Safe Prototype-Based Component Evolution

Component-based programming is currently carried out using mainstream object-oriented languages. These languages have to be used in a highly disciplined way to guarantee flexible component composition and extensibility. This paper investigates abstractions for component-oriented programming on the programming language level. We propose a simple prototype-based model for first-class components on top of a class-based object-oriented language. The model is formalized as an extension of Featherweight Java. Our calculus includes a minimal set of primitives to dynamically build, extend, and compose software components, while supporting features like explicit context dependencies, late composition, unanticipated component extensibility, and strong encapsulation. We present a type system for our calculus that ensures type-safe component definition, composition, and evolution

Programming language abstractions for extensible software components

With the growing demand for software systems that can cope with an increasing range of information processing tasks, the reuse of code from existing systems is essential to reduce the production costs of systems as well as the time to manufacture new software applications. For this reason, component-based software development techniques gain increasing attention in industry and research. Component technology is driven by the promise of building software by composing off-the-shelf components provided by a software component industry. Therefore, component technology emphasizes the independent development and deployment of components. Even though components look like perfect reusable assets, they embody general software solutions that need to be adapted to deploymentspecific needs and therefore cannot be deployed "as is" in general. Furthermore, as architectural building blocks, components are subject to continuous change. For these reasons, it is essential that components can easily be extended by both the component manufacturer to create new versions of components and by thirdparties that have to adapt components for use in specific software systems. Since in both cases concrete changes cannot be foreseen in general, mechanisms to integrate unanticipated extensions into components and component systems are required. While today many modern programming techniques, methodologies, and languages provide means that are well suited for creating static black-box components, the design and implementation of extensible components and extensible software systems often remains a challenge. In practice, extensibility is mostly achieved through ad-hoc techniques, like the disciplined use of design patterns and component frameworks, often in conjunction with meta-programming. The use of design patterns and component frameworks requires a rigorous coding discipline and often forces programmers to write tedious "boilerplate" code by hand, which makes this approach fragile and error-prone. Meta-programming techniques on the other hand are rather code-centric and mostly source code-based. Therefore, they are often not very suitable for today's component technology practice that stresses the binary reuse of black-box components. In this thesis I argue that technical difficulties in the development of extensible software components are due to the lack of appropriate programming language abstractions. To overcome the problems, concrete programming language mechanisms are proposed to facilitate the creation of extensible software. The proposed language features are strongly typed to help the programmer extend systems safely and consistently. The first part of the thesis illustrates the vision of truly extensible software components by proposing a simple theoretical model of first-class components built on top of a conventional class-based object-oriented language. This typed model includes a small set of primitives to dynamically build, compose, and extend software components safely, while supporting features like explicit context dependencies, late composition, unanticipated component extensibility, and strong encapsulation. The second part takes some ideas from the theoretical model and applies them in the design of the programming language Keris. Keris extends Java with an expressive module system featuring extensible modules. The main contributions are: A module system that combines the benefits of classical module systems for imperative languages with the advantages of modern component-oriented formalisms. In particular, modules are reusable, generic software components that can be linked with different cooperating modules without the need for resolving context dependencies by hand. A module composition scheme based on aggregation that makes the static architecture of a system explicit, and A type-safe mechanism for extending atomic modules aswell as fully linked systems statically by replacing selected subsystems with compatible versions without needing to re-link the full system. The extensibility mechanism is non-invasive; i.e. it preserves the original version and does not require access to source code. The overall design of the language was guided by the aim to develop a pragmatic, implementable, and conservative extension of Java which supports software development according to the open/closed principle: Systems written in Keris are closed in the sense that they can be executed, but they are open for unanticipated extensions that add, refine, or replace modules or whole subsystems. The last part of the thesis finally presents a case study which compares an extensible Java compiler implemented using mainstream object-oriented language features with one that was written in Keris. It shows how in practice, extensible modules can be used to develop extensible systems safely and efficiently

Temporal interpretation and cross-linguistic variation. A formal semantic analysis of temporal and aspectual reference in Hausa and Medumba

This thesis investigates temporal and aspectual reference in the typologically unrelated African languages Hausa (Chadic, Afro–Asiatic) and Medumba (Grassfields Bantu). It argues that Hausa is a genuinely tenseless language and compares the interpretation of temporally unmarked sentences in Hausa to that of morphologically tenseless sentences in Medumba, where tense marking is optional and graded. The empirical behavior of the optional temporal morphemes in Medumba motivates an analysis as existential quantifiers over times and thus provides new evidence suggesting that languages vary in whether their (past) tense is pronominal or quantificational (see also Sharvit 2014). The thesis proposes for both Hausa and Medumba that the alleged future tense marker is a modal element that obligatorily combines with a prospective future shifter (which is covert in Medumba). Cross-linguistic variation in whether or not a future marker is compatible with non-future interpretation is proposed to be predictable from the aspectual architecture of the given language.Die vorliegende Dissertation untersucht Zeitinterpretation in den afrikanischen Sprachen Hausa (Tschadisch, Afro-asiatisch) und Medumba (Grassfields Bantu). Es wird gezeigt, dass Hausa eine im technischen Sinne tempuslose Sprache ist. Außerdem wird die Interpretation von Sätzen ohne Tempus im Hausa mit der im Medumba verglichen, wo Tempusmarkierung optional und abgestuft ist. Das Verhalten der optionalen Temporalmarkierer im Medumba motiviert eine Quantorenanalyse dieser Morpheme. Im Vergleich mit anderen abgestuften Tempussprachen liefert Medumba somit neue Evidenz für die Annahme, dass Sprachen sich darin unterscheiden, ob die Semantik ihrer Tempusmorpheme über Zeitintervalle quantifiziert oder Zeitvariablen restringiert (vgl. Sharvit 2014). Es wird sowohl für Hausa als auch für Medumba eine modale Semantik für die jeweiligen Futurmarkierer vorgeschlagen. Diese treten obligatorisch mit einem semantischen Prospektiv- bzw. Futurmorphem auf, das im Hausa overt und im Medumba covert realisiert wird. Sprachvergleichend wird argumentiert, dass die Kombinationsmöglichkeiten von semantischem Aspekt in einer Sprache determinieren, ob der Futurmarkierer der jeweiligen Sprache nicht-futurische Lesarten erlaubt

Expansion and fragmentation: internationalization, political change and the transformation of the nation-state

Is the end of the nation-state approaching, now that the international economy takes less and less notice of borders between countries and the European Union has already acquired so much political power? What does national autonomy mean when governments delegate any number of powers to international organizations? Internationalization leads to political change, and the position of the nation-state appears to be undergoing a radical process of erosion. The surprising conclusion of this book is that the political significance of the state will not be lost. The analyses show that both expansion and fragmentation of political power are characteristics of fundamental political change. While it is true that the state is delegating authority and that internationalization is limiting autonomy, the state is also finding new forms of cooperation and coordination, both nationally and internationally, to preserve and even to strengthen its power and autonomy. Contrary to widely held assumptions, the idea of a progressive weakening of the nationstate does not prove tenable

Expansion and Fragmentation

Is the end of the nation-state approaching, now that the international economy takes less and less notice of borders between countries and the European Union has already acquired so much political power? What does national autonomy mean when governments delegate any number of powers to international organizations? Internationalization leads to political change, and the position of the nation-state appears to be undergoing a radical process of erosion. The surprising conclusion of this book is that the political significance of the state will not be lost. The analyses show that both expansion and fragmentation of political power are characteristics of fundamental political change. While it is true that the state is delegating authority and that internationalization is limiting autonomy, the state is also finding new forms of cooperation and coordination, both nationally and internationally, to preserve and even to strengthen its power and autonomy. Contrary to widely held assumptions, the idea of a progressive weakening of the nationstate does not prove tenable

Contrastive Topic: Meanings and Realizations

This dissertation develops a theory of contrastive topics (CTs)—what they mean, and how they are realized. I give a compositional semantics for CT constructions, built on the idea that CT marks anaphora to a complex question in the discourse. The account allows us to maintain an inclusive view of what counts as a contrastive topic, making reasonable predictions about sentences with CT phrases of difference types, in various combinations, and across various speech acts. Empirically, the dissertation focuses on contrastive topic marking in English and Mandarin Chinese. In English, CT phrases are typically realized with a “rising” prosody. I offer an explicit model that predicts the intonational features of English sentences containing contrastive topics. In Mandarin, sentences with CTs often exhibit the discourse particle -ne. I provide a detailed description of the particle’s distribution, and offer the first sustained argument that -ne is a CT marker

Spectres of the past : a comparative study of the role of historiography and cultural memory in the development of nationalism in modern Scotland and Greece

The purpose of this thesis is to explore themes in the development of national ideology in Scotland and Greece largely in the nineteenth and twentieth centuries. The analysis consists of two pairs of case studies where, using the comparative method, the role of historiography in providing ‘mental maps’, precise boundaries for the nation in space and time, its application in constructing a national consensus on an acceptable past, and the use of the latter in consolidating a national identity, are explored in detail. This process followed intricate paths in both Scotland and Greece and displayed rifts and fissures in patterns thought common in the development of nationalism in Europe. The fundamental ideological challenges to which significant segments of the Scottish and Greek society had to respond are shown to have influenced their respective societies’ worldview until the present time. The resilience of a number of different valid perceptions of Scotland in the nineteenth century and the dichotomy between equally possible concepts of Greece demonstrate, in concluding, the fluidity of national identity and indeterminacy of their modern ethnogenesis as late as the eve of the Great War

Formaciones imaginarias del diseñador gráfico en el discurso del campo académico.

En este trabajo se describe un proyecto de tesis doctoral en el que se analiza el discurso sobre el diseñador gráfico. Se parte del supuesto de que existe una tricotomía de su perfil: 1) el campo profesional, 2) el campo educativo y, 3) el campo académico. Proponemos que dicha tricotomía permite la identificación de imaginarios sobre el tema, y no solo eso, sino que también aporta elementos que conforman la identidad (Bauman, 2002) de un diseñador gráfico. La pregunta de investigación es ¿Cuál es la identidad discursiva del diseñador gráfico en el campo académico? La investigación descrita es de tipo cualitativo y deductivo; para la construcción la identidad discursiva (Van Dijk, T; 2008) del diseñador gráfico, se toman en cuenta diversas publicaciones: principalmente investigaciones y breves artículos difundidos en comunidades/foros de reflexión y debate en torno a la temática, además de memorias de congresos y libros. En apoyo al desarrollo del proyecto se ha diseñado un Laboratorio de Intervención en el Diseño, cuyos objetivos son impulsar el desarrollo social y cultural de los diseñadores gráficos por medio de la investigación, educación continua, producción y vinculación. En un primer acercamiento a las formaciones imaginarias (Pêcheux, 1978) sobre la identidad del diseñador gráfico se centran en el grado de erudición para la ejecución de su trabajo, en la cultura que demuestran y en la autonomía con la que producen