DemystifyingObject-Oriented Programming

Download Files:https://github.com/sketchings/oop-basics

https://joind.in/talk/1a5fa

Presented by: Alena Holligan• Wife and Mother of 3 young children

• PHP Teacher at Treehouse

• Group Leader (PHPDX, Women Who Code Portland)

www.sketchings.com@sketchingsalena@holligan.us

Terminologythe single most important part

PART 1: TermsClass (properties, methods)

Object

Instance

Abstraction

Encapsulation

PART 2: PolymorphismInheritance

Interface

Abstract Class

Traits

Part 3: ADDED FEATURESNamespaces

Type Declarations

Static Methods

Magic Methods

Magic Constants

Class

A template/blueprint that facilitates creation of objects. A set of program statements to do a certain task. Usually represents a noun, such as a person, place or thing.

Includes properties and methods — which are class functions

Object

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/copy of an object

There might be one or several objects, but an instance is a specific copy, to which you can have a reference

class User { //class private $name; //property public getName() { //method echo $this->name; }}

$user1 = new User(); //first instance of object

$user2 = new User(); //second instance of object

Abstraction

Managing the complexity of the system

Dealing with ideas rather than events

This is the class architecture itself.

Use something without knowing inner workings

Encapsulation

Binds together the data and functions that manipulate the data, and keeps both safe from outside interference and misuse.

Properties

Methods

ScopeControls who can access what. Restricting access to some of the object’s components (properties and methods), preventing unauthorized access.

Public - everyone

Protected - inherited classes

Private - class itself, not children

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

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.

https://github.com/sketchings/oop-basics

PART 2: PolymorphismD-R-YSharing Code

pol·y·mor·phism /ˌpälēˈmôrfizəm/The condition of occurring in several different forms

BIOLOGY

GENETICS

BIOCHEMISTRY

COMPUTING

TermsPolymorphism

Inheritance

Interface

Abstract Class

Traits

Inheritance: passes knowledge down

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

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; echo "<br />”;

$developer->skills = array("JavasScript", "HTML", "CSS");$developer->skills[] = “PHP";

echo $developer->getSkillsString();

When run, the script returns:

Ms Jane Smith, Developer

JavasScript, HTML, CSS, PHP

Interface

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

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

An abstract class is a mix between an interface and a class. It can define functionality as well as interface.

Classes extending an abstract class must implement all of the abstract methods defined in the abstract class.

abstract class User { //class

public $name; //property

public getName() { //method echo $this->name; }

abstract public function setName($name); //abstract method}

class Developer extends User { public setName($name) { //implementing the method …

Traits

Composition

Horizontal Code Reuse

Multiple traits can be implemented

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();

When run, the script returns:

Ms Jane Smith

Spoon, Fork, Knife

Challenges1. Change to User class to an abstract class.

2. Extend the User class for another type of user, such as our Developer example

3. Add an Interface for the Developer Class (or your own class)

4. Add a trait to the User

https://github.com/sketchings/oop-basics

Part 3: Added FeaturesNamespaces

Type Declarations

Magic Methods

Magic Constants

Static Methods

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, along with aliasing

namespace myUser;

class User { //class

public $name; //property

public getName() { //method

echo $this->name;

}

public function setName($name);

}

class Developer extends \myUser\User { … }

Available Type DeclarationsPHP 5.4

Class/Interface,

self, array,

callable

PHP 7

bool

float

int

string

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

$lonestar = new Conference(); $lonestar->title = ”Lone Star PHP”; $lonestart->addAttendee($user); echo implode(", “, $lonestar->getAttendees());

When the script is run, it will return the same result as before:

Ms Jane Smith

Magic Methods

Setup just like any other method

The Magic comes from the fact that they are triggered and not called

For more see http://php.net/manual/en/language.oop5.magic.php

Magic Constants

Predefined functions in PHP

For more see http://php.net/manual/en/language.constants.predefined.php

Magic Methods and Constantsclass User { protected $name; protected $title; public function __construct($name, $title) { $this->name = $name; $this->title = $title; } public function __toString() { return __CLASS__. “: “ . $this->getFormattedSalutation(); } ... }

Creating / Using the Magic Method$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

Adding a Static Methodsclass User { public $encouragements = array( “You are beautiful!”, “You have this!”, public static function encourage() { $int = rand(count($this->encouragements)); return $this->encouragements[$int]; } ... }

Using the Static Methodecho User::encourage();

When the script is run, it will return the same result as before:

You have this!

Challenges1. Define 2 “User” classes in one file using namespacing

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

• Group Leader (PHPDX, Women Who Code Portland)

www.sketchings.com @sketchingsalena@holligan.us

Download Files: https://github.com/sketchings/oop-basics

https://joind.in/talk/1a5fa