Recommending Framework Extension Examples

The use of software frameworks enables the delivery of common functionality but with significantly less effort than when developing from scratch. To meet application specific requirements, the behavior of a framework needs to be customized via extension points. A common way of customizing framework behavior is by passing a framework related object as an argument to an API call. Such an object can be created by subclassing an existing framework class or interface, or by directly customizing an existing framework object. However, to do this effectively requires developers to have extensive knowledge of the framework's extension points and their interactions. To aid the developers in this regard, we propose and evaluate a graph mining approach for extension point management. Specifically, we propose a taxonomy of extension patterns to categorize the various ways an extension point has been used in the code examples. Our approach mines a large amount of code examples to discover all extension points and patterns for each framework class. Given a framework class that is being used, our approach aids the developer by following a two-step recommendation process. First, it recommends all the extension points that are available in the class. Once the developer chooses an extension point, our approach then discovers all of its usage patterns and recommends the best code examples for each pattern. Using five frameworks, we evaluate the performance of our two-step recommendation, in terms of precision, recall, and F-measure. We also report several statistics related to framework extension points.