Best way to do multiple constructors in PHP
I'd probably do something like this:
<?php
class Student
{
public function __construct() {
// allocate your stuff
}
public static function withID( $id ) {
$instance = new self();
$instance->loadByID( $id );
return $instance;
}
public static function withRow( array $row ) {
$instance = new self();
$instance->fill( $row );
return $instance;
}
protected function loadByID( $id ) {
// do query
$row = my_awesome_db_access_stuff( $id );
$this->fill( $row );
}
protected function fill( array $row ) {
// fill all properties from array
}
}
?>
Then if i want a Student where i know the ID:
$student = Student::withID( $id );
Or if i have an array of the db row:
$student = Student::withRow( $row );
Technically you're not building multiple constructors, just static helper methods, but you get to avoid a lot of spaghetti code in the constructor this way.
The solution of Kris is really nice, but I prefer a mix of factory and fluent style:
<?php
class Student
{
protected $firstName;
protected $lastName;
// etc.
/**
* Constructor
*/
public function __construct() {
// allocate your stuff
}
/**
* Static constructor / factory
*/
public static function create() {
return new self();
}
/**
* FirstName setter - fluent style
*/
public function setFirstName($firstName) {
$this->firstName = $firstName;
return $this;
}
/**
* LastName setter - fluent style
*/
public function setLastName($lastName) {
$this->lastName = $lastName;
return $this;
}
}
// create instance
$student= Student::create()->setFirstName("John")->setLastName("Doe");
// see result
var_dump($student);
?>
PHP is a dynamic language, so you can't overload methods. You have to check the types of your argument like this:
class Student
{
protected $id;
protected $name;
// etc.
public function __construct($idOrRow){
if(is_int($idOrRow))
{
$this->id = $idOrRow;
// other members are still uninitialized
}
else if(is_array($idOrRow))
{
$this->id = $idOrRow->id;
$this->name = $idOrRow->name;
// etc.
}
}