PHP: Hypertext Preprocessor

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PHP - OOP

PHP : Intro

Dimitar DanailovSenior Developer at 158ltd.com

dimityr.danailov[at]gmail.comGithub

Slide ShareFounder at VarnaIT

Senior Developer at 158ltd.com

Topics Today

● Object-oriented programming Overview● Objects & Classes● Abstraction and encapsulation● Inheritance● Polymorphism● Class Diagrams

OOP

Object-oriented programming (OOP) is a programming paradigm that represents concepts as "objects" that have data fields (attributes that describe the object) and associated procedures known as methods. Objects, which are usually instances of classes, are used to interact with one another to design applications and computer programs. C++, Objective-C, Smalltalk, Java and C# are examples of object-oriented programming languages.

OOP (2)

● Objects & Classes● Abstraction and encapsulation● Inheritance● Polymorphism

Objects & Classes

What is an object

Objects are the elements through which we perceive the world around us. All objects have these characteristics : ● Identity● State ● Behaviour

<?php//Objects

$human = new stdClass();$human->gender = 'm';$human->age = 35;$human->name = 'Todor Dimov';

$child1 = new stdClass();$child1->name = 'Dimo Todorov';

$child2 = new stdClass();$child2->name = 'Todorka Todorova';

$human->childrens = array($child1, $child2);

var_dump($human);?>

Classes (classification of objects)

A class is a group of objects with same attributes and behavior. The characteristics of a class are : ● A name● Attributes● Methods / Functions

<?php/* Classes */class Human { private $name = null; private $gender = null; private $age = null; private $childrens = array(); public function __construct($name, $gender, $age, $childrens = array()) { $this->name = $name; $this->gender = $gender; $this->age = $age; $this->childrens = $childrens; }}/* … */?>

<?php/* ... */

$child1 = new Human('Dimo Todorov', 'm', 12);$child2 = new Human('Todorka Todorova', 'f', 16);

$childrens = array($child1, $child2);$human = new Human('Todor Dimov', 'm', 35, $childrens);

var_dump($human);

?>

Abstraction and encapsulation

Abstraction

In computer science, abstraction is the process by which data and programs are defined with a representation similar in form to its meaning (semantics), while hiding away the implementation details. Abstraction tries to reduce and factor out details so that the programmer can focus on a few concepts at a time. A system can have several abstraction layers whereby different meanings and amounts of detail are exposed to the programmer.

Encapsulation

Encapsulation is the practice of including in an object everything it needs hidden from the other objects in the system.

Inheritance

Inheritance

In object-oriented programming (OOP), inheritance is a way to establish Is-a relationships between objects. In classical inheritance where objects are defined by classes, classes can inherit attributes and behavior from pre-existing classes called base classes, superclasses, or parent classes.

// Inheritanceclass Human { private $name = null; private $gender = null; private $age = null; public function __construct($name, $gender, $age) { $this->name = $name; $this->gender = $gender; $this->age = $age; } static function prinHello($name) { echo 'Hello, ' . $name; } private function greetings() { echo 'Greetings'; }}

class ParentClass extends Human { private $name = null; private $gender = null; private $age = null; private $childrens = array(); public function __construct($name, $gender, $age) { $this->name = $name; $this->gender = $gender; $this->age = $age; } public function getName() { //$this->greetings(); return parent::prinHello($this->name); } public function getChildrens() { return $this->childrens; } public function setChildren(Child $child) { $this->childrens[] = $child; }}

Class Child extends Human { private $parents = array(); public function __construct($name, $gender, $age) { $this->name = $name; $this->gender = $gender; $this->age = $age; } public function getParents() { return $this->parents; } public function setParent(ParentClass $parent) { $this->parents[] = $parent; }}

Polymorphism

Polymorphism

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

Abstract Classes

Class Abstraction

PHP 5 introduces abstract classes and methods. Classes defined as abstract may not be instantiated, and any class that contains at least one abstract method must also be abstract. Methods defined as abstract simply declare the method's signature - they cannot define the implementation.

<?phpabstract class AbstractHuman { private $name = null; private $gender = null; private $age = null; public function __construct($name, $gender, $age) { $this->name = $name; $this->gender = $gender; $this->age = $age; } abstract public function getName(); abstract public function setName($name); abstract public function getGender(); abstract public function setGender($gender); abstract public function getAge(); abstract public function setAge($age);}?>

<?phpclass ParentClass extends AbstractHuman { public function getName() { return $this->name; } public function setName($name) { $this->name = $name; } public function getGender() { return $this->gender; } public function setGender($gender) { $this->gender = $gender; } // ...}?>

Interfaces

Object Interfaces

Object interfaces allow you to create code which specifies which methods a class must implement, without having to define how these methods are handled.Interfaces are defined using the interface keyword, in the same way as a standard class, but without any of the methods having their contents defined.All methods declared in an interface must be public, this is the nature of an interface.

<?php// Interfacesinterface iHuman { public function getName(); public function setName($name); public function getGender(); public function setGender($gender); public function getAge(); public function setAge($age);}?>

<?phpclass ParentClass implements iHuman { public function getName() { return $this->name; } public function setName($name) { $this->name = $name; } public function getGender() { return $this->gender; } public function setGender($gender) { $this->gender = $gender; } // ...}?>

Class Diagrams

Questions ?

Dimitar DanailovSenior Developer at 158ltd.com

dimityr.danailov[at]gmail.comGithub

Slide ShareFounder at VarnaIT

Senior Developer at 158ltd.com