Software maintenance is the lifecycle activity that consumes the greatest amount of resources. Maintenance is a difficult task because of the size of software systems. Much of the time spent on maintenance is spent trying to understand source code. Refactoring offers a way to improve source code design and quality. We present an approach to refactoring that is based on the functionality of source code. Sets of heuristics are captured as patterns of source code. Refactoring opportunities are located using these patterns, and dependencies are verified to check if the located refactorings preserve the dependencies in the source code. Our automated tool performs the functional-based refactoring opportunities detection process, verifies dependencies, and performs the refactorings that preserve dependencies. These refactorings transform the source code into a series of functional regions of code, which makes it easier for developers to locate code they are searching for. This also creates a chunked structure in the source code, which helps with bottom-up program comprehension. Thus, this process reduces the amount of time required for maintenance by reducing the amount of time spent on program comprehension. We perform case studies to demonstrate the effectiveness of our automated approach on two open source applications. / Thesis (Master, Computing) -- Queen's University, 2007-10-05 12:48:56.977

Software reconnaissance is a very useful technique for locating features in software systems that are unfamiliar to a developer. The technique was, however, limited by the need to execute multiple test cases and record the components used in each one. Tools that recorded the execution traces of a program made it more practical to use the software reconnaissance technique. Diver was developed as an execution trace visualization tool using sequence diagrams to display the dynamic behaviour of a program. The addition of software reconnaissance to Diver and its trace-focused user interface feature improved the filtering of the Eclipse environment based on the contents of execution traces and led to a very powerful program comprehension tool. Myers' work on Diver was grounded in cognitive support theory research into how to build tools. He conducted a user study to validate the work done on Diver, but the study's findings were limited due to a number of issues. In this thesis, we expand on the study run by Myers, improve on its design, and investigate if software reconnaissance improves Diver's effectiveness and efficiency for program comprehension tasks. We also analyze the influence of software reconnaissance on the interactions of Diver's users, which allows us to identify successful usage patterns for completing program comprehension and feature location tasks. We research the connection between cognitive support theory and the design of Diver and use the study to attempt to validate the cognitive support offered by Diver. Finally, we present the results of a survey of the study participants to determine the usefulness, ease of use, and ease of learning of the tool. / Graduate / 0984

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Program comprehension, i.e. to understand from its source code what a computer programdoes, is crucial for change and maintenance in software development. In this thesis, it is lookedfor innovative documentation techniques and tools that support program comprehension, butthat are also conform to agile values and principles – commonly, documentation is consideredcritical due to the agile value “working software over comprehensive documentation.”1 First,a research framework is developed that embodies detailed requisites for such techniques andtools. Apart from its internal use for examining techniques and tools subsequently obtainedfrom a literature search, this framework is intended to be likewise employed by software practitioners.Eventually, the findings of a series of survey studies conducted in an industrial softwareorganization for the primary purpose of evaluating the obtained techniques and tools are analyzed.Three innovative techniques that meet all requisites are revealed. These are regarded bypractitioners independently from the support of program comprehension as helpful for a changeimpact analysis conducted by non-developers. Therefore, a requisite deduced from the highestpriority in agile software development – customer satisfaction – is met. It says that a techniqueor tool has to directly induce a benefit for non-developer stakeholders besides the benefits forthem which are indirectly induced by the support of program comprehension, e.g. a potentiallyimproved source code quality. Further, the technique most beneficial for developers as well asfor non-developers among the three techniques is identified, which bases on design rationales– textual information related to the source code that states the reasons why a part of the programhas been implemented in a certain way. Secondarily, the studies revealed that the researchframework is difficult to understand for practitioners due to its unstructured form. / Program: Magisterutbildning i informatik

One important aspect of the quality of programming languages is the effort required by a programmer to understand code written in the language. A historical case where this issue was at the forefront was in the debate between the proponents of high-level languages (HLL) and Assembly languages, where the main argument for HLLs were that they were easier for people to understand. Being one out of a series of articles arguing for a unified theory for software engineering, this article proposes the use of a specific theoretical model from the discipline of cognitive psychology as a tool for predicting language comprehension effort. Describing human problem solving faculties, the ACT-R model [Anderson and Lebiere 1998] predicts that the effort of understanding a program written in C is only 36,5% of the effort of understanding a comparable program written in Assembly. In order to validate the theory, an experiment was performed where a number of engineering students were exposed to tasks of program comprehension. This empirical assessment demonstrated that the effort of understanding a program written in C is 32,5% of the effort of understanding a comparable program written in Assembly. Comparing the results of the theoretical predictions and the empirical assessments of program comprehension effort, we find that the theoretical model performs surprisingly well. The prediction error for the execution of an Assembly program was 5,1% while the error for C was 6,8%. The prediction error for the ratio between the two program languages amounted to 12,6%. / <p>QC 20130618</p>

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The need of change is essential for a software system to reside longer in the market. Change implementation is only done through the maintenance and successful software maintenance gives birth to a new software release that is a refined form of the previous one. This phenomenon is known as the evolution of the software. To transfer software from lower to upper or better form, maintainers have to get familiar with the particular aspects of software i.e. source code and documentation. Due to the poor quality of documentation maintainers often have to rely on source code. So, thorough understanding of source code is necessary for effective change implementation. This study explores the code comprehension problems discussed in the literature and prioritizes them according to their severity level given by maintenance personnel in the industry. Along with prioritizing the problems, study also presents the maintenance personnel suggested methodologies for improving code comprehension. Consideration of these suggestions in development might help in shortening the maintenance and evolution time. / Usman Akhlaq Mirpur, Azad Kashmir, Pakistan Muhammad Usman Yousaf Bhimber, Azad Kashmir, Pakistan