<?php

/* overloading in php refers to dynamically create undeclared data members at
 * runtime, resulting JS style ability to assign properties to an object
 * via -> operator, this is done by use of __set and __get magic methods, also
 * it is possible to bypass data members access levels this way
 *
 * __call is used to resolve call to undefined/protected/private methods, or
 * to perform clever yet ugly error handling
 *
 * http://www.php.net/manual/en/language.oop5.overloading.php
 *
 */

error_reporting(E_ALL | E_STRICT);

class Base {
    protected $data;

    function __construct() {
        $this->data = array();
    }

    /* gets called upon unresolved setter */
    public function __set($key, $val) {
        if (!is_a($val, 'Closure'))
            print "calling __set('$key','$val')" . PHP_EOL;
        $this->data[$key] = $val;
    }

    /* gets called upon unresolved getter */
    public function __get($key) {
        print "calling __get('$key')" . PHP_EOL;
        if (array_key_exists($key, $this->data)) {
            return $this->data[$key];
        }

        $trace = debug_backtrace();
        trigger_error(
            'Undefined property via __get(): ' . $key .
            ' in ' . $trace[0]['file'] .
            ' on line ' . $trace[0]['line'],
            E_USER_NOTICE);
        return null;
    }

    /* http://www.phpied.com/javascript-style-object-literals-in-php/ */
    function __call($name, $args) {
        if (is_callable($this->$name)) {
            array_unshift($args, $this);
            return call_user_func_array($this->$name, $args);
        }

        return null;
    }

    /**  As of PHP 5.1.0  */
    public function __isset($key)
    {
        echo "Is '$key' set?\n";
        return isset($this->data[$key]);
    }

    /**  As of PHP 5.1.0  */
    public function __unset($key)
    {
        echo "Unsetting '$key'\n";
        unset($this->data[$key]);
    }

}

echo "<pre>\n";

$obj = new Base();

$obj->a = 1;
echo $obj->a . "\n\n";

var_dump(isset($obj->a));
unset($obj->a);
var_dump(isset($obj->a));
echo "\n";


/* JS like ability to assign a function to a property */
$obj->foo = function () {
    print "hello, world! from method created at runtime!" . PHP_EOL;
};
$obj->foo();


echo '</pre>'

?>