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How does one overload Arithmetic operators for a class?


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Thanks for the extra info ignace, I had guessed self was referencing the current class some how but I'm curious what it is actually doing.. "granted I know this syntax is wrong" but I imagine its something like this:

function add(new thisClass($b))

Is that an accurate depiction of what is happening? Btw I didn't end up using the keyword since I wasn't sure what it was doing and I wanted to include more parameters.

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Like scootsah already pointed out, you can only pass instances of A. That said to make it more natural to arithmetic operations you can use value objects.


class Operand {
  private $value;
  public function __construct($val) { $this->value = $val; }
  public function add(self $other) {
    return new static($this->value + $other->value);
  public function __toString() {
    return $this->value;
So your program can look like this:


$seven = new Operand(7);
$four = new Operand(4);

$eleven = $seven->add($four);

var_dump($seven, $four, $eleven);

$twentytwo = $eleven->add($seven)->add($four);

var_dump($seven, $four, $eleven, $twentytwo);
As you can see $seven remains the value 7 as does $four remain the value 4 throughout the application.
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