Bad code 11: Parallel inheritance hierarchies)

The parallel inheritance system is actually a casual modification (Shotgun surgery. In this case, whenever you add1Subclass, which must also be added to another class1Sub-classes. If you find that the class name prefix of an inheritance system is exactly the same as the class name prefix of another inheritance system, it smells bad.

The general strategy to eliminate this repeatability is to allow an inherited system instance to reference another inherited system instance. If you make persistent efforts to useMove Method(Shift function)AndMove Field(Moving fields),To cancel the inheritance system of the reference end.