Evolution of method invocation and object instantiation patterns in a PHP ecosystem

PHP is one of the most frequently used scripting languages for server-side programming, since approximately 75% of successful web applications have been developed with PHP. The main benefits of PHP are its low learning curve and the rich variety of dynamic features that it offers. These benefits have contributed towards the development of a large community of programmers around PHP, which in turn created a vast ecosystem of applications and frameworks. In this study we have empirically investigated ten famous PHP frameworks / applications and over 240 MLOC in order to explore their internal structure. More specifically, we present some demographics on method invocation and object instantiation patterns, empowered by the dynamic nature of the PHP language. To present the results we employ statistical methods inspired by ecology. In particular, we explore the diversity and dominance of these patterns, by using the Shannon-Wiener diversity index and a Dominance index that has been originally developed for Plankton. The main conclusion of our study is that the employment of the patterns, is related to developers, and therefore we can observe normality and repetition with small diversions.