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