Classes

Classes

Get started with object-oriented programming in PHP, learning about classes, properties, and methods with real-world examples. 

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Classes are a fundamental part of modern PHP development. Think of a class as a blueprint - it defines what properties (data) and methods (functions) your objects will have. Objects in PHP help you organize related data and functionality together in a reusable way.

Basic Class Structure

Let's start with a simple example:

 1class Product
 2{
 3    public string $name;
 4    public float $price;
 5 
 6    public function isExpensive(): bool
 7    {
 8        return $this->price > 100;
 9    }
10}
11 
12$product = new Product();
13$product->name = "Phone";
14$product->price = 99.99;
15 
16echo $product->name; // returns “Phone”
17var_dump($product->isExpensive());  // returns false

class Product
{
    public string $name;
    public float $price;

    public function isExpensive(): bool
    {
        return $this->price > 100;
    }
}

$product = new Product();
$product->name = "Phone";
$product->price = 99.99;

echo $product->name; // returns “Phone”
var_dump($product->isExpensive());  // returns false

This simple example shows the basic components of a class: • Properties ($name, $price) store data

• Methods (isExpensive()) define behavior

• The $this keyword refers to the current object

Constructor Method

We can make our class better by using a constructor - a special method that runs when creating a new object. It lets you add data while creating a new object instance:

1class Product
2{
3    public function __construct(
4        public string $name,
5        public float $price
6    ) {}
7}
8 
9$product = new Product("Phone", 99.99);

class Product
{
    public function __construct(
        public string $name,
        public float $price
    ) {}
}

$product = new Product("Phone", 99.99);

Access Levels

PHP provides three visibility levels for properties and methods:

1class Product
2{
3    public string $name;      // Accessible from anywhere
4    private float $price;     // Only inside this class
5    protected bool $active;   // Inside this class and child classes
6}

class Product
{
    public string $name;      // Accessible from anywhere
    private float $price;     // Only inside this class
    protected bool $active;   // Inside this class and child classes
}

Inheritance

Classes can inherit properties and methods from other classes. This is useful when you have similar types of objects that share common features but need some additional functionality. Instead of duplicating code, you can extend a base class:

 1class Product
 2{
 3    public function __construct(
 4        public string $name,
 5        public float $price
 6    ) {}
 7 
 8    public function hasDiscount(): bool
 9    {
10        return $this->price < 100;
11    }
12 
13    public function getDescription(): string
14    {
15        return "{$this->name} costs {$this->price}€";
16    }
17}
18 
19class DigitalProduct extends Product
20{
21    public function __construct(
22        public string $name,
23        public float $price,
24        public string $downloadLink
25    ) {}
26 
27    public function download(): string
28    {
29        return "Downloading {$this->name} from {$this->downloadLink}";
30    }
31}
32 
33$course = new DigitalProduct('PHP Course', 99.99, 'course.zip');
34echo $course->getDescription();  // inherited method
35echo $course->hasDiscount();     // inherited method
36echo $course->download();        // new method

class Product
{
    public function __construct(
        public string $name,
        public float $price
    ) {}

    public function hasDiscount(): bool
    {
        return $this->price < 100;
    }

    public function getDescription(): string
    {
        return "{$this->name} costs {$this->price}€";
    }
}

class DigitalProduct extends Product
{
    public function __construct(
        public string $name,
        public float $price,
        public string $downloadLink
    ) {}

    public function download(): string
    {
        return "Downloading {$this->name} from {$this->downloadLink}";
    }
}

$course = new DigitalProduct('PHP Course', 99.99, 'course.zip');
echo $course->getDescription();  // inherited method
echo $course->hasDiscount();     // inherited method
echo $course->download();        // new method

When you start working with Laravel, you'll use classes extensively. Every model, controller, and service in Laravel is a class. This foundation will help you understand Laravel's structure better.