code: function _gpfGetClassDefinition (constructor) {
      var classDef,
          uid = constructor[_GPF_CLASSDEF_MARKER];
      if (undefined === uid) {
          classDef = new _GpfOldClassDefinition(constructor);
          constructor[_GPF_CLASSDEF_MARKER] = classDef._uid;
      } else {
          classDef = _gpfClassDefinitions[uid];
      }
      return classDef;
  }
docs: Retrieves (or allocate) the class definition object
  
  @param {Function} constructor Class constructor
  @return {gpf.ClassDefinition}