PIE: A Tool for Visualizing the Life Cycle of Design Patterns in Open Source Software Projects

Design patterns are employed in source code to solve commonly occurring programming tasks using understood best practices. Object-oriented design patterns usually span multiple classes and objects and play an integral role in the way object-oriented software is built. One challenge with using object-oriented design patterns is that over the life of a project, these patterns can undergo both planned and unplanned changes. Unplanned changes are often the result of bug fixes or code maintenance tasks that modify a design pattern as a side effect. Furthermore, these unplanned changes can result in increased brittleness of the code and can compromise the overall stability of the software. Over the lifetime of a software project, developers may only become aware of these unplanned changes when the code brittleness results in a software bug. To improve developers' understanding of object-oriented design pattern evolution, we introduce the design Pattern Instance Explorer (PIE) _ an exploratory visualization tool that enable developers to visualize a git repository's object-oriented design patterns and their life cycles. In addition to discussing the PIE tool, we provide examples of how this tool can be used to identify and understand design pattern changes. Tool demonstration video: https://www.youtube.com/watch?v=Gkn_5q8_Awg