Unleash the power of PHP 5

[DJMaze]

Ok many people are sceptic about PHP 5, many noticed bugs and issues and others unleash the new powers.

WARNING this article is NOT for the PHP savvy who just got his hands on a book like "PHP for dummies". This article explains a big advantage of PHP 5 so you must be familiar with objects and variable types.

First all the code:

PHP Code:

class Readonly
{
    private $data; # Read only properties
    public function __construct($data)
    {
        $this->data = $data;
    }
    public function __get($key)
    {
        if (isset($this->data[$key])) { return $this->data[$key]; }
        trigger_error('Undefined property: '.$key);
        return null;
    }
    public function __set($key, $val) { throw new Exception('Disallowed to set property: '.$key); }
    public function __isset($key) { return isset($this->data[$key]); }
    public function __unset($key) { throw new Exception('Disallowed to unset property: '.$key); }
    public function get_data() { return $this->data; }
} 


LOL you thought it was big

The class name should already explain what it does. It makes the data inside to be read-only so that a programmer can't overwrite the data.
Why? Well simple, who has ever write code and forgot the second '=' in an expression where it should have been '=='?
Right we all do, and its a pain to track the bug down. Sometimes you don't even notice it

Cool, now tell me, how does it work......

PHP Code:

// The data
$data = array(
    'var1' => 'value 1',
    'var2' => 'value 2',
    'var3' => 'value 3',
);
// Make it read-only
$data = new Readonly($data);

// Read a property
echo 'Value of var1 is: '.$data->var1;

// Test if we can change the value
$data->var1 = 'foobar'; // exception thrown 


Thanks to PHP 5 we now can eliminate some bugs we normaly produce, because every time we try to set a property the script dies on us.
This is something which is NOT possible in PHP 4 and a bug like:

PHP Code:

if ($data['var1'] = 'foo')
{
  // execute
} 


happens all the time.

I haven't explained bugs but if you all like to know more about this then i will write a follow about the above code including more examples and known bugs.

[Belisarius]

Ack, I hate the fact you can do that in PHP. I love the improved object support in PHP, but I'm always going to think of weak-typing as a design flaw (declaring data as an array AND and object).

Another thing I'd love to see in PHP is Threads. There's fork(), but that's really not a good way to work in a concurrent environment, not on the level with pthreads in C and Threads in Java.

The implicit methods __set, __get, etc are neat - I hadn't thought of using them in this fashion (in fact, I hadn't given them much thought before), but I'll give it a shot.

[DJMaze]

__set, __get, etc. have a bug "by design"

PHP Code:

class a
{
    private $data = array();
    public function __set($key, $val)
    {
        echo "a sets $key to $val";
        $this->data[$key] = $val;
    }
}

class b
{
    public function foo()
    {
        echo $this->val;
    }
}

$a = new a();
$a->b = new b();
$a->b->c = 'foobar'; // error 


That's why my above script puts objects in public and variables in the protected $data.

Same bug happens on arrays

PHP Code:

$a = new a();
$a->b = array('entry');
echo $a->b[0]; // error