Question

There is an object, which can be initialized by id or by name.

How it should be handled?

class user
{
    function __construct($id_or_name)
    {
        if ( is_numeric($id_or_name) )
        {
            $this->id = $id_or_name;
            $this->populate_by_id($this->id)
        }
        else
        {
            $this->name = $id_or_name;
            $this->populate_by_name($this->name)
        }
    }
    ...
}

$user1 = new user('Max');
$user2 = new user(123);

Is it ok for general practice?

Answer 1

IMHO, it’s terrible. Introuce two static “fabric methods”, one receive string, other – integer. And construct your object differently:

class user
{
    //you might want make it private
    function __construct($id_or_name)
    {
        //common logic
    }

    static function construct_by_name($name){
        $result = new self();
        $result->name = $name; //note you are in the same class, so you may directly assign private variables
        $result ->populate_by_name($result ->name);
        return $result;
    }

    static function construct_by_id($id){
        $result = new self();
        $result->id= $id; //note you are in the same class, so you may directly assign private variables
        $result ->populate_by_id($result ->id);
        return $result;
    }
}