The document provides an extensive overview of object-oriented programming (OOP), detailing crucial concepts such as classes, objects, abstraction, encapsulation, polymorphism, and inheritance. It includes practical coding examples, live coding demos, and challenges to reinforce understanding of OOP principles and its implementation in PHP. Additional topics covered include interfaces, abstract classes, traits, magic methods, namespaces, and type declarations.

1. Demystifying
Object-Oriented Programming
Download Files:
https://github.com/sketchings/oop-basics
https://joind.in/talk/9b82a

2. Why Object-Oriented?
What’s wrong with procedural?

3. Terminology
the single most important part for learning

4. PART 1: Terms
Class
properties
methods
Object
Instance

5. PART 2: Terms
Abstraction
Encapsulation
Scope

6. PART 3: Terms
Polymorphism
Inheritance
Interface
Abstract Class
Traits

7. PART 4: Extra Features
Static Methods
Magic Methods
Magic Constants
Namespaces
Type Declarations

8. Class
Template or Blueprint
Combination of Variables and Functions
A template/blueprint that facilitates creation of objects.
House
Human (DNA)
A set of program statements to do a certain task.
Usually represents a noun, such as a person, place or thing.
Includes properties (variables) and methods (functions)

9. Object
Entity Created from the Class
Consists of both data and procedures
Instance of a class.
In the real world object is a material thing that can be seen and touched.
In OOP, object is a self-contained entity that consists of both data and procedures.

10. Instance
Single occurrence of an object
James Titcumb (@asgrim)
There might be one or several objects, but an instance is a specific copy, to which you assign a reference
Jim, Jimmy, Jamie, Jimbo

11. class User { //class
private $name; //property
public function getName() { //method
echo $this->name; //current object property
}
}
$user1 = new User(); //first instance of object
$user2 = new User(); //second instance of object

12. PART 2: Terms

13. Abstraction
Hides all but the relevant data about an object in
order to reduce complexity and increase efficiency.
Use something without knowing inner workings
Managing the complexity of the system
existing in thought or as an idea but not having a physical or concrete existence.
relating to or denoting art that does not attempt to represent external reality, but rather seeks to achieve its effect using shapes, colours, and textures.
consider something theoretically or separately from (something else).
Use something like: care, computer

14. Encapsulation
Binds together the data
and functions that
manipulate the data, and
keeps both safe from
outside interference and
misuse.
Properties
Methods
Helps you keep things together

15. Scope
Controls who has access
Public - everyone
Protected - inherited classes
Private - class itself, not children
Restricting access to some of the object’s components (properties and methods), preventing unauthorized access.

16. LIVE CODING DEMO!
Challenges:
1. Create a new class with properties and methods
2. Instantiate a new user with a different name and title
3. Throw an error because your access is too restricted.

17. class User {
protected $name;
protected $title;
public function getFormattedSalutation() {
return $this->getSalutation();
}
protected function getSalutation() {
return $this->title . " " . $this->name;
}
public function getName() {
return $this->name;
}
public function setName($name) {
$this->name = $name;
}
public function getTitle() {
return $this->title;
}
public function setTitle($title) {
$this->title = $title;
}
}

18. Creating / Using the object Instance
$user = new User();
$user->setName("Jane Smith");
$user->setTitle("Ms");
echo $user->getFormattedSalutation();
When the script is run, it will return:
Ms Jane Smith

19. PART 3:
Polymorphism
D-R-Y
Sharing Code

20. pol·y·mor·phism
/ˌpälēˈmôrfizəm/
The condition of occurring in several different forms
BIOLOGY
GENETICS
BIOCHEMISTRY
COMPUTING
Polymorphism describes a pattern in object oriented programming in which classes have different functionality while sharing a common interface

21. Terms
Polymorphism
Inheritance
Interface
Abstract Class
Traits

22. Inheritance
Pass information down
Only a single source
Subclass, parent and a child relationship, allows for reusability, extensibility.
Additional code to an existing class without modifying it. Uses keyword “extends”
NUTSHELL: create a new class based on an existing class with more data, create new objects based on this class

23. LIVE CODING DEMO!
Challenge: Extend the User class for another type of user, such as our Developer example

24. Creating a child class
class Developer extends User {
public $skills = array(); //additional property
public function getSalutation() {//override method
return $this->title . " " . $this->name. ", Developer";
}
public function getSkillsString(){ //additional method
return implode(", ",$this->skills);
}
}

25. Using a child class
$developer = new Developer();
$developer->setName(”Jane Smith”);
$developer->setTitle(“Ms”);
echo $developer->getFormatedSalutation();
echo "<br />”;
$developer->skills = array("JavasScript", "HTML", "CSS");
$developer->skills[] = “PHP";
echo $developer->getSkillsString();

26. When run, the script returns:
Ms Jane Smith, Developer
JavasScript, HTML, CSS, PHP

27. Interface
Requirements for a particular TYPE of object
TIPS:
Multiple Interfaces may be implemented
All methods are public
May contain CONSTANT that cannot be overridden
Interface, specifies which methods a class must implement.
All methods in interface must be public.
Multiple interfaces can be implemented by using comma separation
Interface may contain a CONSTANT, but may not be overridden by implementing class

28. LIVE CODING DEMO!
Challenge:
1. User implements UserInterface
2. Add additional interfaces for the Developer Class

29. interface UserInterface {
public function getFormattedSalutation();
public function getName();
public function setName($name);
public function getTitle();
public function setTitle($title);
}
class User implements UserInterface { … }

30. Abstract Class
Mix between an interface and a class.
Classes extending an abstract class must implement all
of the abstract methods defined in the abstract class.
It can define functionality as well as interface.
abstract methods cannot be private because they are not a full method

31. LIVE CODING DEMO!
Challenge: User extend abstractUser

32. abstract class User { //class
public $name; //property
public function getName() { //method
echo $this->name;
}
abstract public function setName($name); //abstract method
}
class Developer extends User {
public setName($name) { //implementing the method
…

33. Traits
Horizontal Code Reuse
Multiple traits may be used

34. LIVE CODING DEMO!
Challenge: Add a trait to the User

35. Creating Traits
trait Toolkit {
public $tools = array();
public function setTools($task) {
switch ($task) {
case “eat":
$this->tools[] =
array("Spoon", "Fork", "Knife");
exit;
...
}
}
public function showTools() {
return implode(", ",$this->skills);
}
}

36. Using Traits
class Developer extends User {
use Toolkit;
...
}
$developer = new Developer();
$developer->setName(”Jane Smith”);
$developer->setTitle(”Ms”);
echo $developer;
echo "<br />";
$developer->setTools("Eat");
echo $developer->showTools();

37. When run, the script returns:
Ms Jane Smith
Spoon, Fork, Knife

38. Part 3: Added Features
Magic Methods
Magic Constants
Static Methods
Namespaces
Type Declarations

39. Magic Methods
Setup just like any other method
Magic because triggered and not called
For more see http://php.net/manual/en/language.oop5.magic.php

40. Magic Constants
Predefined constants in PHP
For more see http://php.net/manual/en/language.constants.predefined.php

41. LIVE CODING DEMO!
class User {
…
public function __construct($name, $title) {
$this->name = $name;
$this->title = $title;
}
public function __toString() {
return __CLASS__. “: “
. $this->getFormattedSalutation();
}
}
$user = new User("Jane Smith","Ms");
echo $user;
When the script is run, it will return the same result as before:
User: Ms Jane Smith

42. Static Methods
You do NOT have to instantiate an object first

43. LIVE CODING DEMO!
public $encouragements = array(
“You are beautiful!”,
“You have this!”,
public static function encourage()
{
$int = rand(count($this->encouragements));
return $this->encouragements[$int];
}
echo User::encourage();
When the script is run, it will return:
You have this!

44. Namespaces
Prevent Code Collision
Help create a new layer of code encapsulation
Keep properties from colliding between areas of your code
Only classes, interfaces, functions and constants are affected
Anything that does not have a namespace is considered in
the Global namespace (namespace = "")

45. Namespaces
Must be declared first (except 'declare)
Can define multiple in the same file
You can define that something be used in the "Global"
namespace by enclosing a non-labeled namespace in {}
brackets.
Use namespaces from within other namespaces

46. namespace myUser;
class User { //class
public $name; //property
public getName() { //method
echo $this->name;
}
public function setName($name);
}
class Developer extends myUserUser { … }

47. Type Declarations
PHP 5.4
Class/Interface,
self, array,
callable
PHP 7
bool
float
int
string

48. Type Declarations
class Conference {
public $title;
private $attendees = array();
public function addAttendee(User $person) {
$this->attendees[] = $person;
}
public function getAttendees(): array {
foreach($this->attendees as $person) {
$attendee_list[] = $person;
}
return $attendee_list;
}
}

49. Using Type Declarations
$phpuk = new Conference();
$phpuk->title = ”PHP UK Conference 2017”;
$phpuk->addAttendee($user);
echo implode(", “, $phpuk->getAttendees());
When the script is run, it will return the same result as before:
Ms Jane Smith

50. Challenges
1. Define 2 “User” classes. Call both classes from the same file
2. Try defining types AND try accepting/returning the wrong types
3. Try another Magic Method http://php.net/manual/en/
language.oop5.magic.php
4. Add Magic Constants http://php.net/manual/en/
language.constants.predefined.php
5. Add and use a Static Method
https://github.com/sketchings/oop-basics

51. Resources
LeanPub: The Essentials of Object Oriented PHP
Head First Object-Oriented Analysis and Design

52. Presented by: Alena Holligan
• Wife and Mother of 3 young children
• PHP Teacher at Treehouse
• Portland PHP User Group Leader
www.sketchings.com
@sketchings
alena@holligan.us
Download Files: https://github.com/sketchings/oop-basics
https://joind.in/talk/9b82a