PHP: How to Pass child class __construct() arguments to parent::__construct()?

Question

I have a class in PHP like so:

class ParentClass {
    function __construct($arg) {
        // Initialize a/some variable(s) based on $arg
    }
}


        

Answer 1

Check out these functions on php.net:

func_get_args
func_num_args

Also, if you want to make an optional argument, you can do this:

class ParentClass {
    function __construct($arg, $arg2="Default Value") {
        // Initialize a/some variable(s) based on $arg
    }
}

Answer 2

parent::__construct( func_get_args() );

Answer 3

Yeah, it's pretty bad practice to make a child class that uses different constructor arguments from the parent. Especially in a language like PHP where it's poorly supported.

Of course, the generic way to pass a set of "whatever arguments we might ever want" in PHP is to pass a single argument consisting of an array of configuration values.

Answer 4

if you get php nested limit error, try this:

$args = func_get_args();
call_user_func_array(array('parent', '__construct'), $args);

Answer 5

There is something like this in php, though a bit verbose:

$args = func_get_args();
call_user_func_array(array($this, 'parent::__construct'), $args);

Answer 6

This can be done in PHP >= 5.6 without call_user_func_array() by using the ... (splat) operator:

public function __construct()
{
    parent::__construct(...func_get_args());
}