Gain insights into object-oriented programming in PHP. Discover classes, objects, methods, inheritance, and more. Build dynamic server-side applications using OOP techniques and PHP database management.

php-lamp.tar.gz

php-db

php-db-challenge

php-composer

php-package-install

php-redirect

Object-oriented programming is perhaps the dominant development paradigm for leading languages including Java, C#, and Python. The rich class and inheritance framework wasn’t fully implemented in modern PHP until 2015, and best practices for object-oriented programming are still emerging.

This course is an introduction to object-oriented programming in PHP. You’ll start with the basics of the OOP paradigm and get familiar with classes, objects, methods, and properties. You’ll then chain methods and properties using the this keyword before working with access modifiers and magic methods. With these basics down, you’ll take a deep dive into object-oriented programming in PHP, including inheritance, abstraction, polymorphism, and namespaces. After exploring exception handling, you’ll use these object-oriented techniques to build, manage, and edit a PHP database.

By the end of this course, you’ll be prepared to build dynamic server-side applications using object-oriented programming in PHP.

Object-Oriented Programming in PHP

# Interface type hinting

In this lesson, we’ll implement type hinting for both abstract classes and real interfaces.


<?php 
abstract class Car { 
  protected $model; 
  protected $height;
  
  abstract public function calcTankVolume(); 
}

// Bmw class
class Bmw extends Car {

  // Properties
  protected $rib;
  
  public function __construct($model, $rib, $height) {
    $this -> model = $model;
    $this -> rib = $rib;
    $this -> height = $height;
  }
  
  // Calculate a rectangular tank volume
  public function calcTankVolume() {
    return $this -> rib * $this -> rib * $this -> height; 
  }
}

// Mercedes class
class Mercedes extends Car {

  // Properties 
  protected $radius;
  
  public function __construct($model, $radius, $height) {
    $this ->model = $model;
    $this -> radius = $radius;
    $this -> height = $height;
  }
  
  // Calculates the volume of cylinder
  public function calcTankVolume() {
    return $this -> radius * $this -> radius * pi() * $this -> height;
  } 
}

// Type hinting ensures that the function gets only objects 
// that belong to the Car interface
function calcTankPrice(Car $car, $pricePerGallon)
{
  return $car -> calcTankVolume() * 0.0043290 * $pricePerGallon . "$"; 
}

// Bmw object
$bmw1 = new Bmw('62182791', 14, 21); 
echo "Full rectangular shaped gas tank costs " . calcTankPrice($bmw1, 3);
echo "\n";

// mercedes Object
$mercedes1 = new Mercedes('12189796', 7, 28); 
echo "Full cylindrical shaped gas tank costs " . calcTankPrice($mercedes1, 3);
?>

# Explanation

First, we create an abstract class named `Car` that both the `Bmw` and the `Mercedes` (and, in fact, any other car model) can inherit from. Then, we refactor the `Bmw` and `Mercedes` classes so that they inherit from the `Car` class. In **line 47**, we type hint the function `calcTankPrice()` with the `Car` interface so that the function can get any object that belongs to this interface. In **line 54** and **59**, we use the function `calcTankPrice()` on both the `Bmw` and `Mercedes` objects.


> **Note:** Whenever we need to type hint more than one related class, we should use interface type hinting.


Learn how to implement type hinting for interfaces.

Introduction

Classes and Objects

Using the $this Keyword for Chaining Methods and Properties

Access Modifiers

Magic Methods and Constants Unveiled

Inheritance in Object-oriented Programming

Abstract Classes and Interfaces

Polymorphism and Type Hinting

Static Methods & Properties and Traits

Namespaces & Dependency Injection

Exception Handling

PHP Database

Model-view-controller (MVC)

Conclusion

Appendix

Type Hinting for Interfaces

Interface type hinting