OO design principles & heuristics
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This document discusses object-oriented (OO) design principles and heuristics. It introduces the concept of OO modeling and its benefits, then outlines several OO design principles including the single responsibility principle, open/closed principle, Liskov substitution principle, interface segregation principle, and dependency inversion principle. For each principle, it provides a definition and example to illustrate how to apply the principle to produce high-quality OO designs. The goal of these principles is to create software that is flexible, understandable, and resilient to changing requirements over time.
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Single Responsibility Principle [Contd.]](https://image.slidesharecdn.com/oodesignprinciplesheuristics-140808094222-phpapp02/85/OO-design-principles-heuristics-10-320.jpg)
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Single Responsibility Principle [Contd.]](https://image.slidesharecdn.com/oodesignprinciplesheuristics-140808094222-phpapp02/85/OO-design-principles-heuristics-11-320.jpg)
![12
Single Responsibility Principle [Contd.]Single Responsibility Principle [Contd.]
What is RESPONSIBILITY?
RESPONSIBILITY is reason for change
How to spot multiple RESPONSIBILITIES?](https://image.slidesharecdn.com/oodesignprinciplesheuristics-140808094222-phpapp02/85/OO-design-principles-heuristics-12-320.jpg)
![13
Single Responsibility Principle [Contd.]Single Responsibility Principle [Contd.]
Example-](https://image.slidesharecdn.com/oodesignprinciplesheuristics-140808094222-phpapp02/85/OO-design-principles-heuristics-13-320.jpg)
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Single Responsibility Principle [Contd.]Single Responsibility Principle [Contd.]
Going from multiple responsibilities to single responsibility -](https://image.slidesharecdn.com/oodesignprinciplesheuristics-140808094222-phpapp02/85/OO-design-principles-heuristics-14-320.jpg)
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Open Close Principle [Contd.]Open Close Principle [Contd.]
Example](https://image.slidesharecdn.com/oodesignprinciplesheuristics-140808094222-phpapp02/85/OO-design-principles-heuristics-16-320.jpg)
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Open Close Principle [Contd.]Open Close Principle [Contd.]
Example](https://image.slidesharecdn.com/oodesignprinciplesheuristics-140808094222-phpapp02/85/OO-design-principles-heuristics-17-320.jpg)
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Liskov Substitution Principle [Contd.]Liskov Substitution Principle [Contd.]
Example](https://image.slidesharecdn.com/oodesignprinciplesheuristics-140808094222-phpapp02/85/OO-design-principles-heuristics-19-320.jpg)
![20
Liskov Substitution Principle [Contd.]Liskov Substitution Principle [Contd.]
Example
Board board = new 3DBoard();
Unit unit = board.getUnits(8,4);](https://image.slidesharecdn.com/oodesignprinciplesheuristics-140808094222-phpapp02/85/OO-design-principles-heuristics-20-320.jpg)
![21
Liskov Substitution Principle [Contd.]Liskov Substitution Principle [Contd.]
Solving 3DBoard problem](https://image.slidesharecdn.com/oodesignprinciplesheuristics-140808094222-phpapp02/85/OO-design-principles-heuristics-21-320.jpg)
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Interface Segregation Principle [Contd.]Interface Segregation Principle [Contd.]
Example](https://image.slidesharecdn.com/oodesignprinciplesheuristics-140808094222-phpapp02/85/OO-design-principles-heuristics-23-320.jpg)
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Interface Segregation Principle [Contd.]Interface Segregation Principle [Contd.]
Separation Through Delegation](https://image.slidesharecdn.com/oodesignprinciplesheuristics-140808094222-phpapp02/85/OO-design-principles-heuristics-24-320.jpg)
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Interface Segregation Principle [Contd.]Interface Segregation Principle [Contd.]
Separation Through Multiple Inheritance](https://image.slidesharecdn.com/oodesignprinciplesheuristics-140808094222-phpapp02/85/OO-design-principles-heuristics-25-320.jpg)
![27
Interface Segregation Principle [Contd.]Interface Segregation Principle [Contd.]
Layering
Naive Layering Scheme](https://image.slidesharecdn.com/oodesignprinciplesheuristics-140808094222-phpapp02/85/OO-design-principles-heuristics-27-320.jpg)
![28
Interface Segregation Principle [Contd.]Interface Segregation Principle [Contd.]
Inverted Layering
Inverted Layers](https://image.slidesharecdn.com/oodesignprinciplesheuristics-140808094222-phpapp02/85/OO-design-principles-heuristics-28-320.jpg)
OO design principles & heuristics
- 1. 1 OO Design Principles and Heuristics Dhaval ShahDhaval Shah
- 2. 2 AgendaAgenda What is OO Modeling? Why OO Modeling? Odors of rotting software Basic OO Principles OO Design Principles and Heuristics Conclusion Case Study
- 3. 3 This session will not:This session will not: Make you an expert in OOAD Turn you into a system architect Provide instruction on UML
- 4. 4 Warning!Warning! Most of these slides maps directly/indirectly to various articles available on the web, especially from objectmentor.com Thanks Bob!
- 5. 5 What is OO ModelingWhat is OO Modeling
- 6. 6 Why OO ModelingWhy OO Modeling To Manage Change To Manage Change To Deliver Faster To Deliver Faster To Deal with Complexity To Deal with Complexity
- 7. 7 Odors of rotting softwareOdors of rotting software RigidityRigidity FragilityFragility ImmobilityImmobility ViscosityViscosity Needless Complexity Needless Complexity Needless Repetition Needless Repetition OpacityOpacity
- 8. 8 OO Design Principles and Heuristics Single Responsibility Principle Open Close Principle Liskov Substitution Principle Interface Segregation Principle Dependency Inversion Principle
- 9. 9 Single Responsibility PrincipleSingle Responsibility Principle A class should have only one reason to change
- 10. 10 Single Responsibility Principle [Contd.]
- 11. 11 Single Responsibility Principle [Contd.]
- 12. 12 Single Responsibility Principle [Contd.]Single Responsibility Principle [Contd.] What is RESPONSIBILITY? RESPONSIBILITY is reason for change How to spot multiple RESPONSIBILITIES?
- 13. 13 Single Responsibility Principle [Contd.]Single Responsibility Principle [Contd.] Example-
- 14. 14 Single Responsibility Principle [Contd.]Single Responsibility Principle [Contd.] Going from multiple responsibilities to single responsibility -
- 15. 15 Open Close PrincipleOpen Close Principle Software entities should be open for extension but closed for modification.
- 16. 16 Open Close Principle [Contd.]Open Close Principle [Contd.] Example
- 17. 17 Open Close Principle [Contd.]Open Close Principle [Contd.] Example
- 18. 18 Liskov Substitution PrincipleLiskov Substitution Principle Subtypes must be substitutable for their base types. LSP is all about inheritance – One must be able to substitute subclass by base class without things going terribly wrong
- 19. 19 Liskov Substitution Principle [Contd.]Liskov Substitution Principle [Contd.] Example
- 20. 20 Liskov Substitution Principle [Contd.]Liskov Substitution Principle [Contd.] Example Board board = new 3DBoard(); Unit unit = board.getUnits(8,4);
- 21. 21 Liskov Substitution Principle [Contd.]Liskov Substitution Principle [Contd.] Solving 3DBoard problem
- 22. 22 Interface Segregation PrincipleInterface Segregation Principle Clients should not be forced to depend upon interfaces that they don't use.
- 23. 23 Interface Segregation Principle [Contd.]Interface Segregation Principle [Contd.] Example
- 24. 24 Interface Segregation Principle [Contd.]Interface Segregation Principle [Contd.] Separation Through Delegation
- 25. 25 Interface Segregation Principle [Contd.]Interface Segregation Principle [Contd.] Separation Through Multiple Inheritance
- 26. 26 Dependency Inversion PrincipleDependency Inversion Principle a.High-level modules should not depend on low- level modules. Both should depend on abstractions b.Abstractions should not depend upon details. Details should depend upon abstractions
- 27. 27 Interface Segregation Principle [Contd.]Interface Segregation Principle [Contd.] Layering Naive Layering Scheme
- 28. 28 Interface Segregation Principle [Contd.]Interface Segregation Principle [Contd.] Inverted Layering Inverted Layers
- 29. 29 ConclusionConclusion Good design is needed to successfully deal with change The main forces driving your design should be high cohesion and low coupling SOLID principles put you on the right path WARNING : these principles cannot be applied blindly :)