Welcome to this Intro to OOP

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Intro to OOP with PHPa basic look into object-oriented programming

What is OOP?

• Object-Oriented Programing • A programming concept that treats functions

and data as objects. • A programming methodology based on

objects, instead of functions and procedures

OOP vs Procedural or Functional

OOP is built around the "nouns", the things in the system, and of what they are capable

Whereas procedural or functional programming is built around the "verbs" of the system, the things you want the system to do

Terminologythe single most important part

Terms

Class (properties, methods) Object Instance Abstraction Encapsulation Inheritance

Terms continued

Polymorphism Interface Abstract Type Hinting vs Type Casting Namespaces

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

“An abstraction denotes the essential characteristics of an object that distinguish it from all other kinds of object and thus provide crisply defined conceptual boundaries, relative to the perspective of the viewer.”— G. Booch This is the class architecture itself.

Encapsulation

Scope. Controls 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; } }

$user = new User(); $user->setName("Jane Smith"); $user->setTitle("Ms"); echo $user->getFormattedSalutation();

Creating / Using the object Instance

When the script is run, it will return:

Ms Jane Smith

class User { protected $name; protected $title; public function __construct($name, $title) { $this->name = $name; $this->title = $title; } public function __toString() { return $this->getFormattedSalutation(); } …

Constructor Method & Magic Methods

$user = new User("Jane Smith","Ms"); echo $user;

Creating / Using the object Instance

When the script is run, it will return:

Ms Jane Smith

the same result as before

Inheritance: passes knowledge downSubclass, 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

class Developer extends User { public $skills = array(); public function getSalutation() { return $this->title . " " . $this->name. ", Developer"; } public function getSkillsString() { echo implode(", ",$this->skills); } }

Creating a child class

$developer = new Developer("Jane Smith", "Ms"); echo $developer; echo "<br />"; $developer->skills = array( "JavasScript", "HTML", “CSS" ); $developer->skills[] = "PHP"; $developer->getSkillsString();

Using a child class

When run, the script returns:

Ms Jane Smith JavasScript, HTML, CSS, PHP

Polymorphism

Polymorphism describes a pattern in object oriented programming in which classes have different functionality while sharing a common interface

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 { … }

Why Use Interface

• Let’s people know how to use and extend class• What’s expected by the program• Type Hinted• Enforces design• Help set up testing• Drupal 8 - extend• Shipping Interface, different with carriers but still

calculate method but works differently

Abstract

An abstract class is a mix between an interface and a class. It can define functionality as well as interface (in the form of abstract methods). 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); } class Developer extends User { … }

Type CASTING

Turning one variable type to another type.

$number_string = “12”;

$number_int = (int) $number_string;

28

Type Hinting

Functions are now able to force parameters to be objects, interfaces, arrays or callable. However, if NULL is used as the default parameter value, it will be allowed as an argument for any later call. If class or interface is specified as type hint, all its children/implementations are allowed.

class Resume { public $user; public function __construct(User $user) { $this->user = $user; }

public function formatHTML() { $string = $this->user->getName(); ...

}

}

$resume = new Resume($developer);

Namespaces

• 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 = "")

Namespaces Continued

• 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, 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 { … }

Explanation CompleteQuestion and Answer Time

Where to go from hereResources and other things to look into

Strengthen your skills

Code Review Pair/peer programing Contribute to open source Open up a personal project Continuous learning Participate in the community, meetups, conferences, forums, teach

Challenges with GIT Repository

1. Change to User class to an abstract class. 2. Throw an error because your access is

too restricted. 3. Extend the User class for another type of

user, such as our Developer example 4. Define 2 “User” classes in one file using

namespacing

Online Training

TeamTreehouse.com (locally on meetup) NomadPHP.com learnhowtoprogram.com (by epicodus) codeschool.com (great GIT intro) freecodecamp.com, coursera.org, udemy.com, lynda.com

BooksDesign Patterns: Elements of Reusable Object-Oriented Software - by Erich Gamma Mastering Object Oriented PHP - by Brandon Savage Python 3 Object Oriented Programming - by Dusty Phillips Practical Object-Oriented Design in Ruby - by Sandi Metz Clean Code / The Clean Coder - both by Robert Martin The Pragmatic Programmer – by Andrew Hunt/David Thomas Refactoring: Improving the Design of Existing Code- by Martin Fowler

Podcasts, Videos and PeopleListing: phppodcasts.com Voices of the Elephpant PHP Roundtable YouTube: PHPUserGroup NomadPHP People: @CalEvans, @LornaJane, @adamculp https://twitter.com/sketchings/lists/php

FinishedQuestion and Answer Time

Thank You from Alena Holligan

Help me improve: Visit Joind.in

Contact Info: www.sketchings.com @sketchings alena@holligan.us