PHP Operator Overloading Demo

<?php

/*
* Demo applicaton to demonstrate userspace operator overloading.
*/

class Vector3 {
    public float $x;
    public float $y;
    public float $z;

    public function __construct(float $x, float $y, float $z) {
        $this->x = $x;
        $this->y = $y;
        $this->z = $z;
    }

    public function abs()
    {
        return sqrt($this->x**2 + $this->y**2 + $this->z**2);
    }

    public function __toString()
    {
        return "({$this->x}, {$this->y}, {$this->z})";
    }

    public static function __add($lhs, $rhs)
    {
        if ($lhs instanceof static && $rhs instanceof static) {
            return new static($lhs->x + $rhs->x, $lhs->y + $rhs->y, $lhs->z + $rhs->z);
        }

        throw new InvalidArgumentException("Both arguments must be a Vector3!");
    }

    public static function __sub($lhs, $rhs)
    {
        if($lhs instanceof static && $rhs instanceof static) {
            return new static($lhs->x - $rhs->x, $lhs->y - $rhs->y, $lhs->z - $rhs->z);
        }

        throw new InvalidArgumentException("Both arguments must be a Vector3!");
    }

    public static function __mul($lhs, $rhs)
    {
        //Multiplication with a scalar
        if (is_numeric($lhs)) {
            return new static($lhs * $rhs->x, $lhs * $rhs->y, $lhs * $rhs->z);
        }
        if (is_numeric($rhs)) {
            return new static($rhs * $lhs->x, $rhs * $lhs->y, $rhs * $lhs->z);
        }

        //Cross product
        if($lhs instanceof static && $rhs instanceof static) {
            return new static(
                $lhs->y * $rhs->z - $lhs->z * $rhs->y,
                $lhs->z * $rhs->x - $lhs->x * $rhs->z,
                $lhs->x * $rhs->y - $lhs->y * $rhs->x);
        }

        throw new InvalidArgumentException("Both arguments must be a Vector3!");
    }

    public static function __concat($lhs, $rhs)
    {
        //Scalar product
        if($lhs instanceof static && $rhs instanceof static) {
            return $lhs->x * $rhs->x + $lhs->y * $rhs->y + $lhs->z * $rhs->z;
        }

        throw new InvalidArgumentException("Both arguments must be a Vector3!");
    }

    public static function __compare($lhs, $rhs)
    {
        //Compare based on absolute values
        if($lhs instanceof static && $rhs instanceof static) {
            return $lhs->abs() <=> $rhs->abs();
        }

        throw new InvalidArgumentException("Both arguments must be a Vector3!");
    }

}

//Vector definition
$a = new Vector3(1, 2, 3);
$b = new Vector3(3, 2, 1);

printf("a: %s\n", $a);
printf("b: %s\n\n", $b);

printf("Addition: %s\n", $a + $b);
printf("Subtraction: %s\n", $a - $b);
printf("Complex operation %s\n", ($a+$b)*2*($a-$b));
printf("Minus a:%s\n", -$a);
printf("Multiplication with scalar: %s\n", 2 * $a);
printf("Multiplication with scalar: %s\n", $a * 2);
printf("Cross product: %s\n", $a * $b);
printf("Dot product: %s\n", $a . $b);

//Comparison test
if ($a == $b) {
    printf("a and b has the same length!\n");
}

if ($a !== $b) {
    printf("a and b are not the same objects!\n");
}