Healthy OOP in Javascript

Transcript

1. 1.

   HEALTHY OBJECT ORIENTED PROGRAMMING IN JAVASCRIPT @MarcoTroisi

2. 2.

   @MarcoTroisi WHY OOP HEALTHY OOP IN JAVASCRIPT

3. 3.

   @MarcoTroisi OBJECTS AS A WAY TO UNDERSTAND THE WORLD HEALTHY

   OOP IN JAVASCRIPT David West quote
4. 4.

   @MarcoTroisi WHERE DOES THE CRITICISM COME FROM HEALTHY OOP IN

   JAVASCRIPT
5. 5.

   @MarcoTroisi HEALTHY OOP IN JAVASCRIPT HEALTHY OOP IN JAVASCRIPT

6. 6.

   @MarcoTroisi IMMUTABILITY HEALTHY OOP IN JAVASCRIPT

7. 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. 8.

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

   world (Yegor Bugayenko, author of “Elegant Objects”) HEALTHY OOP IN JAVASCRIPT
9. 9.

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

10. 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. 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. 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. 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. 14.

    @MarcoTroisi IMMUTABILITY HEALTHY OOP IN JAVASCRIPT PERFORMANCE

15. 15.

    @MarcoTroisi IMMUTABILITY HEALTHY OOP IN JAVASCRIPT THREAD SAFETY

16. 16.

    @MarcoTroisi HEALTHY OOP IN JAVASCRIPT IMMUTABILITY IN JAVASCRIPT

17. 17.

    @MarcoTroisi HEALTHY OOP IN JAVASCRIPT ACCESSORS AND MUTATORS vs USEFUL

    METHODS
18. 18.

    @MarcoTroisi USEFUL METHODS HEALTHY OOP IN JAVASCRIPT OBJECT CLOSER TO

    REAL WORLD ENTITY
19. 19.

    @MarcoTroisi USEFUL METHODS HEALTHY OOP IN JAVASCRIPT NO EXPOSITION OF

    INTERNAL VARIABLES
20. 20.

    @MarcoTroisi USEFUL METHODS HEALTHY OOP IN JAVASCRIPT EXPOSE A SMALL

    NUMBER OF METHODS
21. 21.

    @MarcoTroisi HEALTHY OOP IN JAVASCRIPT REAL WORLD ENTITIES ARE BETTER

    THAN “SERVICES”
22. 22.

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

    ?
23. 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. 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. 25.

    @MarcoTroisi HEALTHY OOP IN JAVASCRIPT USE INTERFACES

26. 26.

    @MarcoTroisi INTERFACES HEALTHY OOP IN JAVASCRIPT - Object is defined

    before implementation
27. 27.

    @MarcoTroisi INTERFACES HEALTHY OOP IN JAVASCRIPT - Object is defined

    before implementation - Easy to write tests
28. 28.

    @MarcoTroisi INTERFACES HEALTHY OOP IN JAVASCRIPT - Object is defined

    before implementation - Easy to write tests - Force objects to adhere to a contract
29. 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. 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. 31.

    @MarcoTroisi INTERFACES HEALTHY OOP IN JAVASCRIPT INTERFACE = ABSTRACT CLASS

    with empty methods
32. 32.

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

    public function makeAndModel() : string; } <?php abstract class PhoneInterface { public function makeAndModel() : string { return ""; } }
33. 33.

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

    PhoneInterface.makeAndModel = function() { return ""; }
34. 34.

    @MarcoTroisi USE INTERFACES HEALTHY OOP IN JAVASCRIPT GIVE AN ABSTRACT

    SIGNATURE TO YOUR OBJECTS
35. 35.

    None
36. 36.

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

    OOP IN JAVASCRIPT