this_staticMethod.php

<?php
class BaseObject
{
    public function differentStaticMethodCallingStyle()
    {
        return [
            'self::' => self::staticMethod(),
            'static::' => static::staticMethod(),
            '$this->' => $this->staticMethod(),
        ];
    }

    protected static function staticMethod()
    {
        return "base object called";
    }
}

class ExtendedObject extends BaseObject
{
    protected static function staticMethod()
    {
        return "extended object called";
    }
}

print_r((new ExtendedObject())->differentStaticMethodCallingStyle());

// Array
// (
//     [self::] => base object called
//     [static::] => extended object called
//     [$this->] => extended object called
// )