Towards XOTcl 2.x∗ A Ten-Year Retrospective and Outlook

Recent work on the Extended Object Tcl (XOTcl) was geared towards the orthogonality, the ease of use, the productiveness, and the tailorability of the language. The result is an innovative object-oriented language framework which serves for developing a family of objectoriented Tcl dialects. In this work-in-progress report, we map the background and history of advanced language constructs (i.e., mixin classes, filters, method delegation) and their continued refinement (i.e., transitive mixins, mixin and filter guards). We present the infrastructure for creating derivative Tcl OO dialects (i.e., creating object systems and their structural relations, assembling base object behavior). A canonical model and infrastructure of parametrization of commands, methods, and objects is presented. Important steps of internal re-designing and refactoring (callstack and object life-time management) are discussed. Execution time and call throughput measurements for basic object life-time and method dispatch scenarios are reported, exhibiting substantial improvements over the XOTcl 1.6.x branch and TclOO 0.6.