Understanding and Refactoring the MATLAB Language

MATLAB is a very popular dynamic “scripting ” language for numerical computations used by scientists, engineers and students world-wide. MATLAB programs are often devel-oped incrementally using a mixture of MATLAB scripts and functions and frequently build upon existing code which may use outdated features. This results in programs that could benefit from refactoring, especially if the code will be reused and/or distributed. Despite the need for refactoring there appear to be no MATLAB refactoring tools available. Correct refactoring of MATLAB is quite challenging because of its non-standard rules for binding identifiers. Even simple refactorings are non-trivial. Compiler writers and software engi-neers are generally not familiar with MATLAB and how it’s used so the problem has been left untouched so far. This thesis has two main contributions. The first is McBench, a tool that helps compiler writers understand the language better. In order to have a systematic approach to the prob-lem, we developed this tool to give us some insight about how programmers use MATLAB. The second contribution is a suite of semantic-preserving refactoring for MATLAB func-tions and scripts including: function and script inlining, converting scripts to functions, extracting new functions, and converting dynamic feval calls to static function calls. These refactorings have been implemented using the McLAB compiler framework, and an evalu-ation is given on a large set of MATLAB programs which demonstrates the effectiveness of our approach. i i