PHP Static Methods

A static method belongs to the class itself, not to any instance. Call it with Class::method() — no new needed.

Defining one

class MathUtils {
    public static function square(int $n): int {
        return $n * $n;
    }

    public static function clamp(int $n, int $min, int $max): int {
        return max($min, min($max, $n));
    }
}

echo MathUtils::square(5);          // 25
echo MathUtils::clamp(120, 0, 100); // 100

self vs static

class Animal {
    public static function fresh(): static {
        return new static();   // returns runtime class
    }
}

class Dog extends Animal {}

$d = Dog::fresh();    // a Dog, not just an Animal

Common uses

• Factories — User::find(42), Money::fromDollars(9.99).
• Helpers — pure functions grouped under a class name.
• Singletons (use sparingly — global state is hard to test).

Watch out

• No $this inside a static method — it doesn't belong to an instance.
• Static methods are global-ish state. They're hard to mock in tests. Prefer constructor injection for collaborators.
• If your "helper" class is mostly static methods that operate on data, it might want to be a regular class with state.

Example

<?php
class Math {
    public static function square(int $n): int {
        return $n * $n;
    }
}
echo Math::square(5);

Exercise

Test yourself