OOP — Static Methods/Properties & Namespaces

static members belong to the class, not each object. Call with ClassName::method() without creating an instance.

Static Methods and Properties

static members belong to the class, not each object. Call with ClassName::method() without creating an instance.

Real-life example: Static is the school bell — one bell for all classrooms, not a separate bell per student.

static method and property

<?php
class Counter {
  public static int $count = 0;

  public static function increment(): void {
    self::$count++;
  }
}

Counter::increment();
Counter::increment();
echo Counter::$count; // 2
?>

Namespaces

Namespaces organize code and avoid name clashes. Declare with namespace App\Models; import with use App\Models\User;

Real-life example: Namespaces are apartment numbers — User in 5A and User in 5B are different people.

namespace and use

<?php
namespace App\Services;

class Mailer {
  public function send(string $to, string $body): void {
    echo "Sent to $to";
  }
}

// another file:
// use App\Services\Mailer;
// $mail = new Mailer();
?>

Iterables

PHP 7.1+ iterable type hint accepts arrays or Traversable objects. foreach works on any iterable.

Real-life example: Iterable is anything you can walk through with foreach — a list, a queue, or a custom collection.

iterable type hint

<?php
function printLessons(iterable $lessons): void {
  foreach ($lessons as $lesson) {
    echo "- $lesson\n";
  }
}

printLessons(["Intro", "Syntax", "MySQL"]);

// Generator is iterable
function rangeGen(int $n): Generator {
  for ($i = 1; $i <= $n; $i++) yield $i;
}
printLessons(rangeGen(3));
?>