Overloading construct in php? - php

Question

does php (5.3.7) supports overloading ?
Example:
class myclass{
function __construct($arg1) { // Construct with 1 param}
function __construct($arg1,$arg2) { // Construct with 2 param}
}
new myclass(123); //> call the first construct
new myclass(123,'abc'); //> call the second

Answer 1

You have to implement the constructor once and use func_get_args and func_num_args like this:
<?php
class myclass {
function __construct() {
$args = func_get_args();
switch (func_num_args()) {
case 1:
var_dump($args[0]);
break;
case 2:
var_dump($args[0], $args[1]);
break;
default:
throw new Exception("Wrong number of arguments passed to the constructor of myclass");
}
}
}
new myclass(123); //> call the first construct
new myclass(123,'abc'); //> call the second
new myclass(123,'abc','xyz'); //> will throw an exception
This way you can support any number of arguments.

Answer 2

No, but it supports optional parameters, or variable number of parameters.
class myclass{
function __construct($arg1, $arg2 = null){
if($arg2 === null){ // construct with 1 param //}
else{ // construct with 2 param //}
}
}
Note that this has the downside that if you actually want to be able to supply null as a second parameter it will not accept it. But in the remote case you want that you can always use the func_* family of utils.

Answer 3

I would define some fromXXX methods that call the __constructor which takes a parameter like id.
<?php
class MyClass {
public function __construct(int $id) {
$instance = Database::getByID($id);
$this->foo = $instance['foo'];
$this->bar = $instance['bar'];
}
public static function fromFoo(string $foo): MyClass {
$id = Database::find('foo', $foo);
return new MyClass($id);
}
}