Abstract classes should be base classes

All abstract classes must be base classes. --Riel's Heuristic 5.6, Arthur Riel 1996

Description

From Arthur Riel 1996:

If a class cannot build objects of itself, then that class must be inherited by some derived class that does know how to build objects. If this is not the case, then the functionality of the base class can never be accessed by any object in the system, and therefore the class is irrelevant in the given domain.

The corollary of which is Riel's heuristic #5.7: All base classes should be abstract classes.

See Also

• Avoid concrete base classes
• Riel's heuristics
• Design maxims