afstudeer presentatie: solid design
Post on 10-May-2015
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Building your application SOLID
Paul de Raaij | @pderaaij2-2-2012
Student HHS
Afstudeerder
Korte introductie
• Afstuderen bij Eleven
Toolbox
Formulierenmodule
DESIGN
SOLID software design
SOLID Design
• Vijf essentiële principes• Geïntroduceerd door Robert C. Martin
Principles of Object-Oriented design
Waarom SOLID design?
Loosely coupled
High cohesion
Reusable
Maintainable
Testable
Waar staat het voor
• Single Responsibility Principle• Open/Closed Principle• Liskov Substitution Principle• Interface Segregation Principle• Dependency Inversion Principle
Single Responsibility Principle
Een klasse heeft maar één reden om te wijzigen
Single Responsibility Principle
1. public class Employee {2. public BigDecimal pay();3. public String getFullName();4. public float getWorkedHours();5. }
Single Responsibility Principle
1. public class Employee {2. public String getFullName();3. }4. 5. public class Cashier {6. public void pay(Employee e);7. }8. 9. public class EmployeeReporter {10. public float getWorkedHours(Employee e);11.}
Open/Closed principle
Entiteiten moeten gesloten zijn voor wijzigingen, maar open voor uitbreidingen
Open/Closed principle
1. public class Musician {2. public void playGuitar();3. }
Open/Closed principle
1. public class Musician {2. public void playGuitar();3. public void playPiano();4. }
Open/Closed principle1. public class Musician {2. public void playInstrument(Instrument i);3. }4. 5. interface Instrument {6. public void play();7. }8. 9. public class Guitar implements Instrument {10. public void play();11.}12. 13.public class Piano implements Instrument {14. public void play();15.}
Liskov Substitution Principle
Functies die gebruik maken van een basis klasse moeten feilloos werken als een
afgeleide klasse wordt gebruikt
Liskov Substitution Principle1. class Rectangle {2. public int width;3. public int height;4. 5. public void setWidth(int w) {}6. public void setHeight(int h) {}7. public int getArea() { return h*w; }8. }9. 10. class Square extends Rectangle {11.
public void setWidth( int w ) { super.setWidth(w); super.setHeight(w); }12.
public void setHeight( int h ) { super.setWidth(h); super.setHeight(h); }13. }14. 15. class TestProgram {16. Rectangle r = new Rectangle();17. r.setWidth(5); r.setHeight(4);18. r.getArea(); // returns 2019. 20. Square s = new Square();21. s.setWidth(5); s.setHeight(4);22. s.getArea(); // returns 16;23. }
Interface Segregation Principle
Functie-specifieke interfaces zijn beter dan één generieke interface
Interface Segregation Principle
1. interface Animal {2. public void bark();3. public void fly();4. public void run();5. public void eatPlant();6. public void eatMeat();7. }8. 9. public Dog implements Animal {10. public void bark();11. public void run();12. public void eatPlant();13. public void eatMeat();14.}15. 16.public Duck implements Animal {17. public void fly();18. public void eatPlant();19.}
1. interface Barkable {2. public void bark();3. }4. 5. interface Flyable {6. public void fly();7. }8. 9. interface Runnable {10. public void run();11. }12. 13. interface Herbivore() {14. public void eatPlant();15. }16. 17. interface Carnivore() {18. public void eatMeat();19. }20. 21. public Dog implements Barkable, Runnable, Herbivore, Carnivore {22. public void bark();23. public void run();24. public void eatPlant();25. public void eatMeat();26. }27. 28. public Duck implements Flyable, Herbivore {29. public void fly();30. public void eatPlant();31. }
Dependency Inversion Principle
A) High level modules mogen niet afhankelijk zijn van low level modules, beide moeten afhangen van abstracties
B) Abstracties mogen niet afhangen van details, details moeten afhangen van abstracties
Dependency Inversion Principle
1. class Band {2. private Singer = new Singer();3. private Musician = new Musician();4. 5. public void playSong();6. }
Dependency Inversion Principle
1. interface MusicalTalent {2. public void useTalent();3. }4. 5. class Musician implements MusicalTalent() {}6. class Singer implements MusicalTalent() {}7. class SingingGuitarist implements MusicalTalent() {}8. 9. class Band { 10. public void playSong( MusicalTalent mt ) {11. mt.useTalent();12. }13.}
Dependency Inversion Principle
1. interface MusicalTalent {2. public void useTalent();3. }4. 5. class Musician implements MusicalTalent() {}6. class Singer implements MusicalTalent() {}7. class SingingGuitarist implements MusicalTalent() {}8. 9. class Band {10.
private List<MusicalTalent> members = new ArrayList<MusicalTalent>();11. public Band() {}12. public void addMember( MusicalTalent mt ) {13. members.add( mt );14. }15. 16. public void playSong() {}17.}
SOLID
Nooit alleen…
… Sterk aan elkaar gekoppeld
Perfect ontwerp bestaat niet
SOLID helpt debalans te vinden
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