Solid principles
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This document discusses the SOLID principles of object-oriented design: - The Single Responsibility Principle states that a class should have one, and only one, reason to change. - The Open/Closed Principle specifies that software entities should be open for extension but closed for modification. - The Liskov Substitution Principle dictates that subclasses should behave in the same way as their parent classes. - The Interface Segregation Principle indicates that client classes should not depend on interfaces they do not use. - The Dependency Inversion Principle asserts that high-level modules should not depend on low-level modules, but both should depend on abstractions. The presentation provides examples of
Solid principles
- 1. SOLID Principles Presented by Mónica Rodrigues January 24rd, 2017
- 2. Contents ➢ What is SOLID ➢ Single responsibility Principle ➢ Open/Closed Principle ➢ Liskov Substitution Principle ➢ Interface Segregation Principle ➢ Dependency Inversion Principle
- 3. Who am I? Mónica Rodrigues Degree in Computer Science Engineer at ISEL Software engineer since 2009 Keywords: Web Applications, ASP.NET MVC, ASP.NET Web API, REST, Javascript, Angular, Best practices, Design patterns, SQL Server and much more..
- 5. “A class should have one and only one reason to change” Single Responsibility Principle
- 6. Single Responsibility Principle Business logic Persistence There are two responsibilities
- 7. Single Responsibility Principle How to solve this?
- 8. Single Responsibility Principle Just create two different classes
- 9. Open/Closed Principle “Software entities should be open for extension, but closed for modification.”
- 10. Open/Closed Principle Humm...and if I need to add a new payment type? You need to modificate this class.
- 11. Open/Closed Principle open for extension close for modification
- 12. Liskov Substitution Principle “Let q(x) be a property provable about objects x of type T. Then q(y) should be provable for objects y of type S where S is a subtype of T” What do you say?
- 13. Liskov Substitution Principle “A subclass should behave in such a way that it will not cause problems when used instead of the superclass.”
- 15. Liskov Substitution Principle Much better
- 16. Interface Segregation Principle “Clients should not be forced to depend upon interfaces that they don't use”
- 18. Interface Segregation Principle WHY????? I don’t need you!!
- 19. Interface Segregation Principle How to solve this?
- 20. Interface Segregation Principle You need to create two interfaces
- 22. Dependency Inversion Principle “High-level modules should not depend on low-level modules. Both should depend on abstractions.” “Abstractions should not depend upon details. Details should depend upon abstractions.”
- 23. Dependency Inversion Principle And if I need to send a notification by SMS? You need to change this.
- 24. Dependency Inversion Principle So, I create an interface and now?
- 26. Dependency Inversion Principle Constructor injection:
- 27. Dependency Inversion Principle Property injection:
- 28. Dependency Inversion Principle Method injection:
- 29. Keep in mind DRY - Don’t repeat yourself + SLAP - Single layer abstraction principle + SOLID BEST DEVELOPER
- 30. Enjoy code and Keep it simple!
- 31. Thank you