CODE EXAMPLE FOR PHP

php

<?php
class PropertyTest
{
    /**  Location for overloaded data.  */
    private $data = array();

    /**  Overloading not used on declared properties.  */
    public $declared = 1;

    /**  Overloading only used on this when accessed outside the class.  */
    private $hidden = 2;

    public function __set($name, $value)
    {
        echo "Setting '$name' to '$value'
";
        $this->data[$name] = $value;
    }

    public function __get($name)
    {
        echo "Getting '$name'
";
        if (array_key_exists($name, $this->data)) {
            return $this->data[$name];
        }

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

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

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

    /**  Not a magic method, just here for example.  */
    public function getHidden()
    {
        return $this->hidden;
    }
}


echo "<pre>
";

$obj = new PropertyTest;

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

";

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

echo $obj->declared . "

";

echo "Let's experiment with the private property named 'hidden':
";
echo "Privates are visible inside the class, so __get() not used...
";
echo $obj->getHidden() . "
";
echo "Privates not visible outside of class, so __get() is used...
";
echo $obj->hidden . "
";
?>