Healthy OOP in Javascript

Transcript

1. HEALTHY OBJECT ORIENTED PROGRAMMING IN JAVASCRIPT @MarcoTroisi

2. @MarcoTroisi WHY OOP HEALTHY OOP IN JAVASCRIPT

3. @MarcoTroisi OBJECTS AS A WAY TO UNDERSTAND THE WORLD HEALTHY

   OOP IN JAVASCRIPT David West quote

4. @MarcoTroisi WHERE DOES THE CRITICISM COME FROM HEALTHY OOP IN

   JAVASCRIPT

5. @MarcoTroisi HEALTHY OOP IN JAVASCRIPT HEALTHY OOP IN JAVASCRIPT

6. @MarcoTroisi IMMUTABILITY HEALTHY OOP IN JAVASCRIPT

7. @MarcoTroisi Classes should be immutable unless there's a very good

   reason to make them mutable....If a class cannot be made immutable, limit its mutability as much as possible. (Joshua Bloch, “Effective Java”) HEALTHY OOP IN JAVASCRIPT

8. @MarcoTroisi ...all classes should be immutable in a perfect object-oriented

   world (Yegor Bugayenko, author of “Elegant Objects”) HEALTHY OOP IN JAVASCRIPT

9. @MarcoTroisi IMMUTABILITY HEALTHY OOP IN JAVASCRIPT PREDICTABILITY (NO SIDE EFFECTS)

10. @MarcoTroisi IMMUTABILITY HEALTHY OOP IN JAVASCRIPT PREDICTABILITY (NO SIDE EFFECTS)

    var Phone = function(phoneMake, phoneModel) { this.make = function() { return phoneMake; } this.model = function() { return phoneModel; } this.equals = function(Phone) { return ( this.make() === Phone.make() && this.model() === Phone.model() ) } } var MotoG = new Phone("Motorola", "Moto G"); var IPhone6 = new Phone("Apple", "iPhone 6"); if (MotoG.equals(IPhone6)) { console.log("equals"); } else { console.log("NOT equals"); }

11. @MarcoTroisi IMMUTABILITY HEALTHY OOP IN JAVASCRIPT PREDICTABILITY (NO SIDE EFFECTS)

    var Phone = function(phoneMake, phoneModel) { this.make = function() { return phoneMake; } this.model = function() { return phoneModel; } this.equals = function(Phone) { return ( this.make() === Phone.make() && this.model() === Phone.model() ) } } var MotoG = new Phone("Motorola", "Moto G"); var IPhone6 = new Phone("Apple", "iPhone 6"); if (MotoG.equals(IPhone6)) { console.log("equals"); } else { console.log("NOT equals"); } // WILL PRINT “NOT equals”

12. @MarcoTroisi IMMUTABILITY HEALTHY OOP IN JAVASCRIPT PREDICTABILITY (NO SIDE EFFECTS)

    var Phone = function(phoneMake, phoneModel) { this.make = phoneMake; this.model = phoneModel; this.equals = function(Phone) { return (this.make === Phone.make && this.model === Phone.model) } } var MotoG = new Phone("Motorola", "Moto G"); var IPhone6 = new Phone("Apple", "iPhone 6"); // Uh-oh MotoG.make = "Apple"; MotoG.model = "iPhone 6"; if (MotoG.equals(IPhone6)) { console.log("equals"); } else { console.log("NOT equals"); }

13. @MarcoTroisi IMMUTABILITY HEALTHY OOP IN JAVASCRIPT PREDICTABILITY (NO SIDE EFFECTS)

    var Phone = function(phoneMake, phoneModel) { this.make = phoneMake; this.model = phoneModel; this.equals = function(Phone) { return (this.make === Phone.make && this.model === Phone.model) } } var MotoG = new Phone("Motorola", "Moto G"); var IPhone6 = new Phone("Apple", "iPhone 6"); // Uh-oh MotoG.make = "Apple"; MotoG.model = "iPhone 6"; if (MotoG.equals(IPhone6)) { console.log("equals"); } else { console.log("NOT equals"); } // WILL PRINT “Equals”

14. @MarcoTroisi IMMUTABILITY HEALTHY OOP IN JAVASCRIPT PERFORMANCE

15. @MarcoTroisi IMMUTABILITY HEALTHY OOP IN JAVASCRIPT THREAD SAFETY

16. @MarcoTroisi HEALTHY OOP IN JAVASCRIPT IMMUTABILITY IN JAVASCRIPT

17. @MarcoTroisi HEALTHY OOP IN JAVASCRIPT ACCESSORS AND MUTATORS vs USEFUL

    METHODS

18. @MarcoTroisi USEFUL METHODS HEALTHY OOP IN JAVASCRIPT OBJECT CLOSER TO

    REAL WORLD ENTITY

19. @MarcoTroisi USEFUL METHODS HEALTHY OOP IN JAVASCRIPT NO EXPOSITION OF

    INTERNAL VARIABLES

20. @MarcoTroisi USEFUL METHODS HEALTHY OOP IN JAVASCRIPT EXPOSE A SMALL

    NUMBER OF METHODS

21. @MarcoTroisi HEALTHY OOP IN JAVASCRIPT REAL WORLD ENTITIES ARE BETTER

    THAN “SERVICES”

22. @MarcoTroisi REAL WORLD ENTITIES HEALTHY OOP IN JAVASCRIPT PasswordEncrypter() PasswordEncryptionService()

    ?

23. @MarcoTroisi REAL WORLD ENTITIES HEALTHY OOP IN JAVASCRIPT /** *

    Interface for an Encrypted Password Object */ var EncryptedPasswordInterface = {} /** * Returns the encrypted value * @return string */ EncryptedPasswordInterface.encryptedValue = function() { return ""; }

24. @MarcoTroisi REAL WORLD ENTITIES HEALTHY OOP IN JAVASCRIPT var Md5EncryptedPassword

    = Object.create(EncryptedPasswordInterface); Md5EncryptedPassword = function(passwordToEncrypt) { this.encryptedValue = function() { // do encryption here… return encryptedPassword; } }

25. @MarcoTroisi HEALTHY OOP IN JAVASCRIPT USE INTERFACES

26. @MarcoTroisi INTERFACES HEALTHY OOP IN JAVASCRIPT - Object is defined

    before implementation

27. @MarcoTroisi INTERFACES HEALTHY OOP IN JAVASCRIPT - Object is defined

    before implementation - Easy to write tests

28. @MarcoTroisi INTERFACES HEALTHY OOP IN JAVASCRIPT - Object is defined

    before implementation - Easy to write tests - Force objects to adhere to a contract

29. @MarcoTroisi INTERFACES HEALTHY OOP IN JAVASCRIPT - Object is defined

    before implementation - Easy to write tests - Force objects to adhere to a contract - Easier to avoid violating the interface segregation principle

30. @MarcoTroisi INTERFACES HEALTHY OOP IN JAVASCRIPT - Object is defined

    before implementation - Easy to write tests - Force objects to adhere to a contract - Easier to avoid violating the interface segregation principle - Easy to swap an object with another

31. @MarcoTroisi INTERFACES HEALTHY OOP IN JAVASCRIPT INTERFACE = ABSTRACT CLASS

    with empty methods

32. @MarcoTroisi INTERFACES HEALTHY OOP IN JAVASCRIPT <?php interface PhoneInterface {

    public function makeAndModel() : string; } <?php abstract class PhoneInterface { public function makeAndModel() : string { return ""; } }

33. @MarcoTroisi INTERFACES HEALTHY OOP IN JAVASCRIPT var PhoneInterface = {}

    PhoneInterface.makeAndModel = function() { return ""; }

34. @MarcoTroisi USE INTERFACES HEALTHY OOP IN JAVASCRIPT GIVE AN ABSTRACT

    SIGNATURE TO YOUR OBJECTS
35. None

36. @MarcoTroisi THANK YOU VERY MUCH! marcotroisi.com @MarcoTroisi github.com/marcotroisi bluefin.com HEALTHY

    OOP IN JAVASCRIPT