Exploring the frequency and change proneness of dynamic feature pattern instances in PHP applications

摘要

Although numerous technologies are available for developing web applications, PHP holds the lions' share of web content today. PHP offers several features that enable developers to easily produce dynamically extendible code, forming an entire ecosystem of standard as well as more 'exotic' opportunities that can be exploited. One reason that drives developers to rely on the dynamic features of a scripting language is to enable effortless functionality extensions. The aim of this work is twofold: initially, we (a) provide an overview of all possible dynamically extendible code patterns (i.e., either through method invocation, or object instantiation) and (b) investigate their frequency by mining the code base of ten milestone PHP projects to identify the subset of patterns that developers actually use. Next, in order to investigate whether the expected flexibility of these patterns stands in practice, we examine if code chunks that instantiate them are more stable than other parts of the code. In particular, we study whether methods that employ dynamic invocation and instantiation patterns are less change prone than the other methods. The findings imply that although a small subset of all the theoretically feasible patterns is actually put to use, the code that is developed upon such patterns is less change prone. (C) 2018 Elsevier B.V. All rights reserved.