Oops in php

B Y G O U R I S H A N K A R R P U J A R
OOPS in PHP

Introduction
 It Provides Modular Structure for your application
 It Makes Easy to maintain Existing Code.
 Here we will be creating Class file & Index file.
 Class file will be filled with Class, Objects, Functions.
 Where as Index file Just Shows the result of that class or
Function when it is called.

List of Data types
 Booleans
 Integers
 Floating Point Numbers
 Strings
 Arrays
 Objects
 Resources – File Handle
 Null
 Call-backs

Objects
 $object = new stdClass;
 $object->name = “Your Name”;
 Echo $object->name;

Index
 Inheritance
 Visibility
 Dependency Injection
 Interface
 Magic Methods
 Abstract
 Static
 Method Chaining
 Auto loading

How to use a Class
$object = new stdClass;
$object->names = [‘BMW’, ‘Audi’, ‘Benz’, ‘Jeep’];
foreach($object->names as $name){
Echo $name . “<br>”;
}

Example
 Student.php
Class Student{
public $name;
public $rollno;
}
Index.php
Require(‘student.php’);
$student = new Student;
$student->name = “Gourish”;
$student->rollno = “7”;
Echo $student->name .‘ has a roll no of ’. $student->rollno;

Using Method
 Student.php
Class Student{
public $name;
public $rollno;
public function sentence(){
return $this->name .‘ has a roll no of ’. $this->rollno;
}
}
Index.php
$student = new Student;
$student->name = “Gourish”;
$student->rollno = 7;
Echo $student->sentence();

Contructors
 This is also called as magic method
 It has 2 Underscores.
 This will be constructed when a class is loaded.
 Public function __Construct(){
echo “Constructed”;
}

Example
 Student.php
Class Student{
public $name;
public $rollno;
public function __construct($name, $rollno){
$this->name = $name;
$this->rollno = $rollno;
}
public function sentence(){
return $this->name .‘ has a roll no of ’. $this->rollno;
}
}
Index.php
$student = new Student(“Gourish”, 7);
Echo $student->sentence();

Inheritance (including)
 Bird.php
Class Bird{
public $canFly;
public $legCount;
public function __construct($canFly, $legCount){
$this->canfly = $canFly;
$this->legCount = $legCount;
}
public function canFly(){
return $this->canFly;
}
public function getlegCount (){
return $this-> legCount;
}
}

 Index.php
Require ”Bird.php”;
$bird = new Bird(true, 2);
Echo $bird->getLegCount();

 Pigeon.php
Class Pigeon extends Bird{
}

 Index.php
Require “Bird.php”
Require “Pigeon.php”;
$pigeon = new Pigeon(true, 2);
Echo $pigeon->getLegCount();
If($pigeon->$canFly()){
echo “Can Fly”;
}

 Can you try it for Penguin

Visibility
 Three access / visibility modifiers introduced in PHP 5, which
affect the scope of access to class variables and functions:
 public : public class variables and functions can be accessed from inside and
outside the class
 protected : hides a variable or function from direct external class access +
protected members are available in subclasses
 private : hides a variable or function from direct external class access +
protected members are hidden (NOT available) from all subclasses
 An access modifier has to be provided for each class instance
variable
 Static class variables and functions can be declared without an
access modifier → default is public

 Penguin.php
Change objects in bird class to Protected.
Class Penguin extends Bird{
public function foo(){
echo $legCount(); // This is picking up from protected object
}
}

Dependency Injection
 Till Now we have understood Inheritance
 But we don’t know how to utilize to its full potential.
 What is Dependency ?
 Create 3 files.
 Index.php
 Chest.php
 Lock.php

 Chest.php
Class Chest{
protected $lock;
protected $isClosed;
public function __construct($lock) {
$this->lock = true;
}
public function close($lock = true) {
if ($lock === true){
$this->lock->lock(); }
$this->isClosed = true;
echo “Closed”;
}
public function open() {
if ($this->lock->isLocked()){
$this->lock ->unlock(); }
$this->isClosed = false;
echo “Open”;
}
public function isClosed(){
return $this->isClosed;
}
}

 Lock.php
Class Lock {
protected $isLocked;
public function lock(){
$this->isLocked = true;
}
public fuction unlock() {
$this->isLocked = false;
}
public function isLocked(){
return $this->isLocked;
}
}

 Index.php
Require ‘chest.php’;
Require ‘lock.php’;
$chest = new Chest(new Lock);
$chest->close();
$chest->open();

Real World Example
 Index Page
 Database
 User

 Database Page
Class Database {
public function query($sql){
// $this->pdo->prepare($sql)->execute();
echo $sql;
}
}

 User.php
Class User {
protected $db;
public function __construct(Database $db){
$this->db = $db;
}
public function create(array $data){
$this->db->query(‘INSERT INTO ‘users’ … ’);
}
}

 Index.php
Require ‘Database.php’;
Require ‘User.php’;
$user = new User(new Database);
$user->create([‘username‘=>’gourish7’]);

Interfaces
 What is Interface ?
 Blueprint for a class.
 3 Methods of file representation
1. Itest.php
2. I_Test.php
3. TestInterface.php

Example 1
 Collection.php
Class Collection {
protected $items = [];
public function add ($value){
$this->items[] = $value;
}
public function set($key, $value){
$this->items[‘$key’] = $value;
}
public function toJson(){
return json_encode($this->items);
}
}

 Index.php
Require ‘Collection.php’;
$c = new Collection()
$c->add(‘name1’);
$c->add(‘name2’);
Echo $c->toJson();
Echo count($c);

Example 2
 TalkInterface.php
Interface Talk{
public function talk();
}

 Company.php
Class Company implements TalkInterface{
public function talk(){
return ‘Welcome Sir/Madam, How can I
help you today’;
}
}

 Person.php
Class Person implements TalkInterface{
public function talk(){
return ‘I need help in Resetting my
Phone’;
}
}

 Index.php
Require ‘TalkInterface.php’;
Require ‘Company.php’;
Require ‘Person.php’;
$company = new Company();
Echo $company->talk();
$person = new Person();
Echo $ person ->talk();

Magic Methods
 What is Magic Method ?
 __construct()
 __set()
 __get()
 __call()
 __toString()

SET Method
 Public function __set($key, $value) {
 $this->set($key, $value);
}
Public function set($key, $value){
$this->items[$key] = $value;
}
Public function all(){
return $this->items;
}
Index.php
$c->align = ‘center’;
Echo ‘pre’, print_r($c ->all());

Get
 Public function __get($value) {
 Return $this-> get(,$value);
}
Public function get($key){
retutn array_key_exists ($key, $this->items) ? $this->items[$key] : null;
}
Index.php
Echo $c->get(‘align’);
Echo $c->align;

Call
 Public function __call($func, $args) {
echo $func.’ has been called with arguments
‘.implode(‘, ’. $args);
}
Index.php
Echo $c->align(‘left’, ‘right’, ‘center’, ‘top’, ‘bottom’);

toString
 Public function __toString(){
 Return $this->jsonSerialize();
}
Public function jsonSerialize(){
return json_encode($this->items);
}
$c->add(‘foo’);
$c->add(‘bar’);
Echo $c;

Abstract
 What is Abstract ?
 It is an interface in which we can define default
implemetations.

Example
 User.php
Abstract Class User{
public function userdetails(){
return ‘Gourishankar’;
}
abstract public function userLocation();
}

 Address.php
Class Address extends User{
public function userAddress(){
return ‘Bengaluru’;
}
public function userLocation(){
return ‘Magadi Road’;
}
}

 Index.php
Require ‘User.php’;
Require ‘Address.php’;
$bar = new Bar;
Echo $bar->userdetails();
Echo $bar->userAddress();
Echo $bar->userLocation();

Static
 What is static ?
 Secret PHP Instance that is dedicated to static
methods & Properties.
 Use only when necessery

 Student.php
Class Student {
public static function name(){
return ‘Gourishankar R Pujar’;
}
}

 Index.php
Require ‘Student.php’;
Echo Student::name();

Method Chaining
 What is Method chaining ?

Example
 Cart.php
Class Cart{
public function order(){
echo “Order <br>”;
return $this;
}
public function book(){
echo “Book”;
}
}

 Index.php
Require “cart.php”;
$cart = new Cart();
$cart->order()->book();

Autoloading
 What is Autoloading ?
 Example – We have to include 10 files in index file
then how we do ?

Method 1
Init.php Index.php
Require_once “Classes/Student.php”;
Require_once “Classes/Parent.php”;
Require_once “Classes/Teacher.php”;
Require_once “Classes/Admin.php”;
Require_once “Classes/Account.php”;
Require_once “init.php”;

Method 2
Init.php Index.php
Spl_autoload_register(function($class)
{
require “class/{$class}.php”;
});
Require_once “init.php”;

Project
 Calculator
 Student Management

Oops in php

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