The SOLID principles are a set of best practices for object-oriented design that focus on creating software with high maintainability and reusability through managing dependencies and responsibilities, including the single responsibility, open-closed, Liskov substitution, interface segregation, and dependency inversion principles. Following these principles helps create flexible, robust software by reducing coupling between modules and increasing cohesion within modules. Adhering to SOLID makes code more readable, maintainable, and predictable when changes need to be made.

1. The SOLID Principles Reading Geek Night

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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

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