Strategies in object-oriented design

This paper presents a study aiming to analyse the design strategies of experts in object-oriented programming. We report an experiment conducted with four experts. Each subject solved three problems. Our results show that three strategies may be used in program design according to the solution structure. An object-centred strategy and a function-centred strategy are used when the solution has a hierarchical structure with vertical communication between objects. In this case, the plan which guides the design activity is declarative. A procedure-centred strategy is used when the solution has a flat structure with horizontal communication between objects. In this case, the plan which guides the design activity is procedural. These results are discussed in relation with results on design strategies in procedural design. Furthermore, our results provide insight into the knowledge structures of experts in object-oriented design. To conclude, we point out limitations of this study and discuss implications of our results for Human-Computer Interaction systems, in particular for systems assisting experts in their design activity

Strategies in object-oriented design

This paper presents a study aiming to analyse the design strategies of experts in object-oriented programming. We report an experiment conducted with four experts. Each subject solved three problems. Our results show that three strategies may be used in program design according to the solution structure. An object-centred strategy and a function-centred strategy are used when the solution has a hierarchical structure with vertical communication between objects. In this case, the plan which guides the design activity is declarative. A procedure-centred strategy is used when the solution has a flat structure with horizontal communication between objects. In this case, the plan which guides the design activity is procedural. These results are discussed in relation with results on design strategies in procedural design. Furthermore, our results provide insight into the knowledge structures of experts in object-oriented design. To conclude, we point out limitations of this study and discuss implications of our results for Human-Computer Interaction systems, in particular for systems assisting experts in their design activity

Design Strategies and Knowledge in Object-Oriented Programming: Effects of Experience

An empirical study was conducted to analyse design strategies and knowledge used in object-oriented software design. Eight professional programmers experienced with procedural programming languages and either experienced or not experienced in object-oriented design strategies related to two central aspects of the object-oriented paradigm: (1) associating actions, i.e., execution steps, of a complex plan to different objects and revising a complex plan, and (2) defining simple plans at different levels in the class hierarchy. As regards the development of complex plans elements attached to different objects, our results show that, for beginners in OOP, the description of objects and the description of actions are not always integrated in an early design phase, particularly for the declarative problem whereas, for the programmers experienced in OOP, the description of objects and the description of actions tend to be integrated in their first drafts of solutions whichever the problem type. The analysis of design strategies reveal the use of different knowledge according to subjects' language experience: (1) schemas related to procedural languages; actions are organized in an execution order, or (2) schemas related to object-oriented languages; actions and objects are integrated, and actions are organised around objects

Knowledge restructing and the development of expertise in computer programming

This thesis reports a number of empirical studies exploring the development of expertise in computer programming. Experiments 1 and 2 are concerned with the way in which the possession of design experience can influence the perception and use of cues to various program structures. Experiment 3 examines how violations to standard conventions for constructing programs can affect the comprehension of expert, intermediate and novice subjects. Experiment 4 looks at the differences in strategy that are exhibited by subjects of varying skill level when constructing programs in different languages. Experiment 5 takes these ideas further to examine the temporal distribution of different forms of strategy during a program generation task. Experiment 6 provides evidence for salient cognitive structures derived from reaction time and error data in the context of a recognition task. Experiments 7 and 8 are concerned with the role of working memory in program generation and suggest that one aspect of expertise in the programming domain involves the acquisition of strategies for utilising display-based information. The final chapter attempts to bring these experimental findings together in terms of a model of knowledge organisation that stresses the importance of knowledge restructuring processes in the development of expertise. This is contrasted with existing models which have tended to place emphasis upon schemata acquisition and generalisation as the fundamental modes of learning associated with skill development. The work reported here suggests that a fine-grained restructuring of individual schemata takes places during the later stages of skill development. It is argued that those mechanisms currently thought to be associated with the development of expertise may not fully account for the strategic changes and the types of error typically found in the transition between novice, intermediate and expert problem solvers. This work has a number of implications for existing theories of skill acquisition. In particular, it questions the ability of such theories to account for subtle changes in the various manifestations of skilled performance that are associated with increasing expertise. Secondly, the work reported in this thesis attempts to show how specific forms of training might give rise to the knowledge restructuring process that is proposed. Finally, the thesis stresses the important role of display-based problem solving in complex tasks such as programming and highlights the role of programming language notation as a mediating factor in the development and acquisition of problem solving strategies