** Taken from “The C+ + Programming Language”
[1] When you program, you create a concrete representation of the ideas in your solution to some
problem. Let the structure of the program reflect those ideas as directly as possible:
[a] If you can think of ‘‘it’’ as a separate idea, make it a class.
[b] If you can think of ‘‘it’’ as a separate entity, make it an object of some class.
[c] If two classes have a common interface, make that interface an abstract class.
[d] If the implementations of two classes have something significant in common, make that
commonality a base class.
[e] If a class is a container of objects, make it a template.
[f] If a function implements an algorithm for a container, make it a template function implementing
the algorithm for a family of containers.
[g] If a set of classes, templates, etc., are logically related, place them in a common namespace.
[2] When you define either a class that does not implement either a mathematical entity like a
matrix or a complex number or a low-level type such as a linked list:
[a] Don’t use global data (use members).
[b] Don’t use global functions.
[c] Don’t use public data members.
[d] Don’t use friends, except to avoid [a] or [c].
[e] Don’t put a ‘‘type field’’ in a class; use virtual functions.
[f] Don’t use inline functions, except as a significant optimization.
