How do I pass specific optional arguments?

Question

I have 2 cases.

• Case 1: pass the name and age.
• Case 2: pass name and gender.

How can I do this?

---

class User {

    function __construct($name=NULL, $gender=NULL, $age=NULL) {
        ...
    }

}

// How do I pass specific arguments here?
$case_1 = new User("Bob", 34);
$case_2 = new User("James", "m");

Answer 1

You can have optional arguments in PHP, but you cannot have either/or arguments as that would require function overloading which is not supported in PHP. Given your example, you must call the constructor as follows:

// How do I pass specific arguments here?
$case_1 = new User("Bob", null, 34);
$case_2 = new User("James", "m");

If you want to eliminate the optional but required to be null argument, you will need to get clever.

Option One: Use a factory. This would require a common argument constructor in conjunction with mutator methods for each of the unique arguments.

class UserFactory {
   public static function createWithGender($name, $gender)
   {
       $user = new User($name);
       $user->setGender($gender);

       return $user;
   }

   public static function createWithAge($name, $age)
   {
       $user = new User($name);
       $user->setAge($age);

       return $user;
   }
}

$case_1 = UserFactory::createWithAge("Bob", 34);
$case_2 = UserFactory::createWithGender("James", "m");

The factory doesn't need to be a separate class, you can alternatively add the static initializers to the User class if desired.

class User {
   function __construct($name = null)
   {
        ...
   }

   public static function createWithGender($name, $gender)
   {
       $user = new static($name);
       $user->setGender($gender);

       return $user;
   }

   public static function createWithAge($name, $age)
   {
       $user = new static($name);
       $user->setAge($age);

       return $user;
   }
}

$case_1 = User::createWithAge("Bob", 34);
$case_2 = User::createWithGender("James", "m");

Option Two: Do some argument detection. This will only work if the arguments are all unique types.

class User {
    public function __construct($name, $second = null) {
        if (is_int($second)) {
            $this->age = $second;
        } else {
            $this->gender = $second;
        }
    }
}

$case_1 = new User("Bob", 34);
$case_2 = new User("James", "m");