Passing arguments to the Class Constructor

Question

How can I pass a arbitrary number of arguments to the class constructor using the Object() function defined below?

<?php

/*
./index.php
*/

function Object($object)
{
    static $instance = array();

    if (is_file('./' . $object . '.php') === true)
    {
        $class = basename($object);

        if (array_key_exists($class, $instance) === false)
        {
            if (class_exists($class, false) === false)
            {
                require('./' . $object . '.php');
            }

            /*
            How can I pass custom arguments, using the
            func_get_args() function to the class constructor?

            $instance[$class] = new $class(func_get_arg(1), func_get_arg(2), ...);
            */

            $instance[$class] = new $class();
        }

        return $instance[$class];
    }

    return false;
}

/*
How do I make this work?
*/

Object('libraries/DB', 'DATABASE', 'USERNAME', 'PASSWORD')->Query(/* Some Query */);

/*
./libraries/DB.php
*/

class DB
{
    public function __construct($database, $username, $password, $host = 'localhost', $port = 3306)
    {
        // do stuff here
    }
}

?>

Solution 1

$klass = new ReflectionClass($classname);
$thing = $klass->newInstanceArgs($args);

Although the need to use reflection suggests that you are overcomplicating something in your design. Why do you want to write this function in the first place?

Solution 2

Instead of your class taking separated parameters I'd have it take an array.

class DB
{
    public function __construct(array $params)
    {
        // do stuff here
    }
}

That way you can pass the direct result of the func_get_args into your constructor. The only problem now is being able to figure out the array key / values.

If anyone else has any ideas I'd also be delighted to know :)

Comments

[Alix Axel]

I got the same idea as well but I was curious to know if something like I described could be done.

[Alix Axel]

Doesn't work. =\ call_user_func_array(array(new $classname(), '__construct'), $args); This works but then I would be calling the constructor twice.

[Deva]

Try it without new $classname().

[Alix Axel]

I admit this function may seem a bit nonsense but I use it for small stuff where a framework may be too bloated. And since it acts as an "autoloader", object constructor and singleton container it does the job perfectly.

[Alix Axel]

BTW, that Reflection class is really handy, is there any crash course available on the new features of PHP 5.3? I checked the PHP manual but is it me or it is lacking a lot of documentation?

[troelskn]

It's not you: The documentation is rather sparse on that. You'll have to do with php.net/oop5.reflection. Also, it has been around since 5.1 (or is it 5.0?), so it's not a new feature of 5.3

[Alix Axel]

Fatal error: Non-static method test::__construct() cannot be called statically

[Deva]

Okay, I've got no more ideas. Thanks for being willing to try.

[Addo Solutions]

Eval is pretty much always a bad idea

[Ahmed Aboud]

if you doing this in a dynamic way use type hints for your arguments in the class constructor