My presentation slides from the recent Reading Geek Night event

1. The SOLID Principles Reading Geek Night

2. My digital identity Blog: http://blog.lukesmith.net Twitter: @lukesmith

3. What the? An acronym of acronyms Collection of best-practices loose-coupling Maintainability Principles – not Rules Focus on dependency management

4. Dependency management Poor dependency management Hard to change Fragile Non-reusable Good dependency management Flexible Robust Reusable

5. Single Responsibility Principle A class should have one, and only one, reason to change

6. Single Responsibility Principle Benefits More readable code More robust More maintainable Smaller functions

7. Open Closed Principle Software entities should be open for extension, but closed for modification

9. Fragile

10. Unpredictable

11. Modules should never change

12. Extend behaviour – add new code

15. Caller should not be surprised by substituting base type for subtype

16. Virtual members must exist in derived classes

18. Must be implemented

19. Expected work

21. Interface Segregation Principle Deals with disadvantage of “fat” interfaces Clients forced to depend on interfaces they don’t use subjected to changes in that interface MembershipProvider – forces 27 methods/properties Benefits Lower coupling – better maintainability Higher cohesion – better robustness

22. Dependency Inversion Principle Depend on abstractions, not concretions

23. Dependency Inversion Principle Modules should not depend on modules implementing details Depend on abstractions

24. Dependency Inversion Principle

25. Further info http://www.butunclebob.com/ArticleS.UncleBob.PrinciplesOfOod