OOP

 

Objects : Things with responsibility.  (interfaces)

 

Encapsulation : Can hiding everything. (not just data)

 

Variation : Find it and hide it. (hide behaviors as object , let it handle the variation , which we don't need to know)

 

 

Program to an interface, not an implementation.

 

Favor object (aggregation) over class inheritance.

 

Instead considering what might force a change to your design, consider what you want to be able to change without redesign.