Object-Orientation Abusers

All these smells are incomplete or incorrect application of object-oriented programming principles.

Alternative Classes with Different Interfaces

Two classes perform identical functions but have different method names. The programmer who created one of the classes probably didn’t know that a functionally equivalent class already existed.

Treatment

• Rename Methods

• Move Method

Payoff

You get rid of unnecessary duplicated code, making the resulting code less bulky.

Refused Bequest

If a subclass uses only some of the methods and properties inherited from its parents, the hierarchy is off-kilter.

Someone was motivated to create inheritance between classes only by the desire to reuse the code in a superclass. But the superclass and subclass are completely different. (Dog inhert from Chair because they both have 4 legs.)

Treatment

• Replace Inheritance with Delegation.

• Get rid of unneeded fields and methods in the subclass.

Temporary Field

Temporary fields get their values (and thus are needed by objects) only under certain circumstances. Outside of these circumstances, they’re empty.

• Temporary fields and all code operating on them can be put in a separate class via Extract Class.

Switch Statements

You have a complex switch operator or sequence of if statements.