PHP Class construct with three optional parameters but one required?

Question

So basically I understand this ...

class User
{
    function __construct($id) {}
}

$u = new User(); // PHP would NOT allow this

I want to be able to do a user look up with any of the following parameters, but at least one is required, while keeping the default error handling PHP provides if no parameter is passed ...

class User
{
    function __construct($id=FALSE,$email=FALSE,$username=FALSE) {}
}

$u = new User(); // PHP would allow this

Is there a way to do this?

Answer 1

You could use an array to address a specific parameter:

function __construct($param) {
    $id = null;
    $email = null;
    $username = null;
    if (is_int($param)) {
        // numerical ID was given
        $id = $param;
    } elseif (is_array($param)) {
        if (isset($param['id'])) {
            $id = $param['id'];
        }
        if (isset($param['email'])) {
            $email = $param['email'];
        }
        if (isset($param['username'])) {
            $username = $param['username'];
        }
    }
}

And how you can use this:

// ID
new User(12345);
// email
new User(array('email'=>'[email protected]'));
// username
new User(array('username'=>'John Doe'));
// multiple
new User(array('username'=>'John Doe', 'email'=>'[email protected]'));