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DemystifyingObject-Oriented Programming
Download Files:https://github.com/sketchings/oop-basics
https://joind.in/talk/9b82a
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)
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.
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 referenceJim, Jimmy, Jamie, Jimbo
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
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 systemexisting 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
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
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.
LIVE CODING DEMO!
Challenges:1. Create a new class with properties and methods2. Instantiate a new user with a different name and title3. Throw an error because your access is too restricted.
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 = $title; } }
Creating / Using the object Instance$user = new User(); $user->setName("Jane Smith"); $user->setTitle("Ms"); echo $user->getFormattedSalutation();
When the script is run, it will return:
Ms Jane Smith
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
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
LIVE CODING DEMO!
Challenge: Extend the User class for another type of user, such as our Developer example
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); } }
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 $developer->getSkillsString();
InterfaceRequirements for a particular TYPE of object
TIPS:
Multiple Interfaces may be implemented
All methods are public
May contain CONSTANT that cannot be overridden
Interface, specifies which methods a class must implement.All methods in interface must be public.Multiple interfaces can be implemented by using comma separationInterface may contain a CONSTANT, but may not be overridden by implementing class
LIVE CODING DEMO!
Challenge: 1. User implements UserInterface2. Add additional interfaces for the Developer Class
interface UserInterface {
public function getFormattedSalutation();
public function getName();
public function setName($name);
public function getTitle();
public function setTitle($title);
}
class User implements UserInterface { … }
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
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 …
Creating Traitstrait 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); } }
Using Traitsclass Developer extends User { use Toolkit; ... }
$developer = new Developer(); $developer->setName(”Jane Smith”); $developer->setTitle(”Ms”); echo $developer; echo "<br />"; $developer->setTools("Eat"); echo $developer->showTools();
Magic Methods
Setup just like any other method
Magic because triggered and not called
For more see http://php.net/manual/en/language.oop5.magic.php
Magic Constants
Predefined constants in PHP
For more see http://php.net/manual/en/language.constants.predefined.php
LIVE CODING DEMO!
class User { … public function __construct($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
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!
NamespacesPrevent 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 = "")
NamespacesMust 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
namespace myUser;
class User { //class
public $name; //property
public getName() { //method
echo $this->name;
}
public function setName($name);
}
class Developer extends \myUser\User { … }
Type Declarationsclass 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; } }
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
Challenges1. 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
Resources
LeanPub: The Essentials of Object Oriented PHP
Head First Object-Oriented Analysis and Design
Presented by: Alena Holligan• Wife and Mother of 3 young children
• PHP Teacher at Treehouse
• Portland PHP User Group Leader
www.sketchings.com @[email protected]
Download Files: https://github.com/sketchings/oop-basics
https://joind.in/talk/9b82a