Question

One of my dreams is to use python rich comparison (something like __eq__) on php objects.

class A {
  public $a = 1;

  public function __eq__($other) {
      return $this->a == $other->a;
  }

}


class B {
  public $a = 2;

  public function __eq__($other) {
      return $this->a == $other->a;
  }

}


class C {
  public $a = 1;

  public function __eq__($other) {
      return $this->a == $other->a;
  }

}

$a = new A();
$b = new B();
$c = new C();

echo $a == $b; //false
echo $a == $c; //true 

I’d like to have some smart mechanism to fast-compare models (objects) on database id, for example.

Is it possible in some way in PHP?

Answer 1

No, it isn’t. A common way to achieve this is to use an equals() method, but there isn’t any magic method. You’ll have to call it manually. For example:

<?php
class User
{
    private $id;

    public function __construct($id)
    {
        $this->id = $id;
    }

    public function getId()
    {
        return $this->id;
    }

    public function equals(User $user)
    {
        return $this->getId() === $user->getId();
    }
}

$user1 = new User(1);
$user2 = new User(2);

var_dump($user1->equals($user2)); // bool(false)
var_dump($user2->equals($user1)); // bool(false)
?>

Which, I think, isn’t much different from:

var_dump($user1 == $user2);
var_dump($user2 == $user1);

Anyway, my example will work even using the == operator, since it will compare the values of all the properties.