A computational solution for the software refactoring problem: from a formalism toward an optimization approach

Abstract: Software Refactoring consists in reconstructing the code design of an object- oriented system without affecting the external functionality. Common refactoring tasks, in the initial steps, detect the source code components to be affected and recommend accurate Refactoring Operations to be applied to those components (an estimation problem). In this document, the author defines, develops and evaluates an Artificial Refactoring Hybrid Adaptive Technique (ArHaT) to estimate refactorings as a combi- natorial model. The author investigated whether Refactoring Impact Prediction yields sets of artificial refactoring operations before implementing them into the code. ArHaT estimates the sets of Refactoring Operations according to some predefined weight values of the quality metrics. The weight values or coefficients capture the developer error-prone knowledge of the code in the objective function. The author conducted several fitness performance evaluations in two open software systems and organized them as a set of experiments. The goal of the experiments is to minimize a ratio between impacted quality metrics and actual quality metrics. Hill-Climbing, Simulated Annealing, and Hybrid Adaptive Evolutionary Algorithm assembled feasible refactorings, yet the latter accomplished the best performance. This research establishes the fundamentals of the automation of the refactoring problem and contributes to reducing the gap between the software defect prediction and the software refactoring.Maestrí

Closing the gap between guidance and practice, an investigation of the relevance of design guidance to practitioners using object-oriented technologies

This thesis investigates if object oriented guidance is relevant in practice, and how this affects software that is produced. This is achieved by surveying practitioners and studying how constructs such as interfaces and inheritance are used in open-source systems. Surveyed practitioners framed 'good design' in terms of impact on development and maintenance. Recognition of quality requires practitioner judgement (individually and as a group), and principles are valued over rules. Time constraints heighten sensitivity to the rework cost of poor design decisions. Examination of open source systems highlights the use of interface and inheritance. There is some evidence of 'textbook' use of these structures, and much use is simple. Outliers are widespread indicating a pragmatic approach. Design is found to reflect the pressures of practice - high-level decisions justify 'designed' structures and architecture, while uncertainty leads to deferred design decisions - simpler structures, repetition, and unconsolidated design. Sub-populations of structures can be identified which may represent common trade-offs. Useful insights are gained into practitioner attitude to design guidance. Patterns of use and structure are identified which may aid in assessment and comprehension of object oriented systems.This thesis investigates if object oriented guidance is relevant in practice, and how this affects software that is produced. This is achieved by surveying practitioners and studying how constructs such as interfaces and inheritance are used in open-source systems. Surveyed practitioners framed 'good design' in terms of impact on development and maintenance. Recognition of quality requires practitioner judgement (individually and as a group), and principles are valued over rules. Time constraints heighten sensitivity to the rework cost of poor design decisions. Examination of open source systems highlights the use of interface and inheritance. There is some evidence of 'textbook' use of these structures, and much use is simple. Outliers are widespread indicating a pragmatic approach. Design is found to reflect the pressures of practice - high-level decisions justify 'designed' structures and architecture, while uncertainty leads to deferred design decisions - simpler structures, repetition, and unconsolidated design. Sub-populations of structures can be identified which may represent common trade-offs. Useful insights are gained into practitioner attitude to design guidance. Patterns of use and structure are identified which may aid in assessment and comprehension of object oriented systems