This paper describes a transformation approach to implementing object oriented extensions of traditional programming languages (OOGPLs), which OOGPLs are implemented using a preprocessor that translates from the program in OOGPL to an equivalent one in a traditional programming language. Some techniques are given to overcome difficulties with allowing polymorphism and dynamic binding. By them the authors have implemented NDOOP which is an object oriented extension of Pascal and NDOOM which is an object oriented extension of Modula 2.