A software design priciple from 'Exceptional C++' of Herb sutter

   A computer science motto: Most problems can be solved by adding a level of indirection. Of course, it's wise to temper this with Occam's Razor: Don't make thisgs more complex than necessary. A proper balance between the two in this case delivers much better reusablity and maintainability at little and no cost -a good deal by all accounts.