A method of operating a computer to generate an object class definition from a procedural program having a main program and a plurality of procedures. The invention determines a set of procedures, including at least one procedure that is actually called by the procedural program during the execution of the main program thereof. The resulting object definition has a main method or procedure that reproduces the behavior exhibited by the procedural program when the main method is invoked or the main procedure is executed. In addition, the invention generates a method in the object class definition corresponding each procedure in the procedural program that is actually used in the procedural program.