Static Properties & Methods In Object-Oriented PHP

Introduction

Static properties and methods belong to the class itself and not to any particular object/instance. You can use it directly using the class name.

To define a static property or method simply add the keyword static before or after the access modifier.

You can now access the static property/method by simply using the scope resolution operator :: after the class name.

When referencing static properties you can either use the keyword self or the class name.

class Transaction {
   // Define $count property as static.
  private static int $count = 15;

  public function __construct(
    public float $amount,
    public string $description,
  ) {
    // Using the keyword `self` to refer the static $count property.
    self::$count++;
  }

  public static getCount() {
    // a static method used to access the static property $count.
    return self::$count;
  }
}

// Using the scope resolution operator to access the static method.
echo Transaction::getCount();

Use-case of static methods and properties

Using static properties and methods are generally bad practice because it’s against the OOP principle. But there are some use-case for it.

• cache some value e.g. as counter
• memorization e.g. cache the result of some expensive operations.
• singleton pattern
• utility functions
• factory pattern
• static closure → to prevent access to object properties