Design Principles

Why OOD?  

        Why should we care about Object Oriented Design?

let me get a classic quote for you:

"Walking on water and developing software from a specification are easy if both are frozen."
- Edward V. Berard

The universal truth of software is "your software is bound to change". Why?

Because, your software solves real life business problems and real life business processes evolve and change - always. Your software does what it is supposed to do today. But, is your software smart enough to support "changes"? If not, you don't have smartly designed software.

Smartly designed software can adjust changes easily; it can be extended, and it is re-usable." And, applying a good "Object Oriented Design" is the key to achieve such a smart design.

 

           Many people have already given lots of thoughts and put a lot of effort on this issue, and they've tried to achieve good Object Oriented Design and identify some basic principles for doing Object Oriented Design (some basic inspirations which you can use to lay out your object oriented design).

There are five principles which are abbreviated as the SOLID principles (thanks to Uncle Bob, the great OOD mentor). 

•       S = Single Responsibility Principle
•       O = Opened Closed Principle
•        L = Liscov Substitution Principle
•        I = Interface Segregation Principle
•        D = Dependency Inversion Principle

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