BrnDmp

PHP OO

INHERITANCE APPROACH
- Advantage
- easy to inherit an implementation
- Disadvantage
- may be difficult to adapt to changing roles

INTERFACE APPROACH
- Advantages
- can be clearer what methods must be implemented.
- A class in another inheritance hierarchy can provide the services of an interface.
- Disadvantage
- may end up with lots of helper classes.

Things to Remember

You can design with an emphasis on either inheritance or interfaces:
- Interfaces show commonality of behavior.
- Inheritance shows commonality of behavior along with commonality of implementation.
- Interfaces are more fluid than inheritance, but you need to use delegation to share common code.
- Inheritance couples the derived classes to the base class, but it allows them to easily share the common code of the base class.