In-class access with self::

PHP course · Intermediate · Lesson 32/115

Learn to access the class's static members from inside with self::.

In-class access with self::

Inside a class, instead of writing the class name to reach a static member, you can use self::. self represents the class where the code is written. Examples: self::$count or self::increment().

This is safer than hardcoding the class name. If you rename the class, self:: still works. It also signals intent: this class's static member.

Important: with self::$count the $ is present (property access). With self::method() there is no $ (method access).

self:: versus $this

self:: and $this point to different things. $this represents the current instance (object); self:: represents the class where the code is written.

From an instance method you can use both: $this->name for an instance property, self::$count for a static property. From a static method, only self:: works; there is no $this.

Example: in a Counter class, the increment() static method does self::$count++; the getCount() static method does return self::$count. No need to repeat the class name.

Exercise Counter: static property and method with self::

Define a Counter class with a public static int $count = 0 property. Add two static methods: increment(): void does self::$count++; getCount(): int does return self::$count. Call Counter::increment() three times, then write echo Counter::getCount() . "\n".

Show example solution

:$count++ in increment, return self::$count in getCount, call Counter::increment() three times, then echo Counter::getCount() . "\n".
Example solution:
<?php
// Write a Counter class with self::
class Counter {
    public static int $count = 0;
    public static function increment(): void {
        self::$count++;
    }
    public static function getCount(): int {
        return self::$count;
    }
}
Counter::increment();
Counter::increment();
Counter::increment();
echo Counter::getCount() . "\n";

Test yourself

What is self:: for?
- To access instance variables
- To access the class's static members from inside
- To access subclass members
- To call the constructor
Show answer

To access the class's static members from inside — Correct. self:: reaches the class's own static members from inside.

Access a static property with self::

class Counter {
    public static int $count = 0;
    public static function increment(): void {
        ____
    }
}

Show answer

class Counter {
    public static int $count = 0;
    public static function increment(): void {
        self::$count++;
    }
}

Match the self:: and $this expressions

self::$count

Static property access
self::method()

Static method call
$this->name

Instance property access
self

Reference to the class itself

In-class access with self::