Question

I have an array in php like this:

$myArray = array(‘name’=>’juank’, ‘age’=>26, ‘config’=>array(‘usertype’=>’admin’,’etc’=>’bla bla’));

I need this array to be accesible along the script to allow changes in any field EXCEPT in the “config” field. Is there a way to protect an array or part of an array from being modified as if it where declared private inside a class? I tried defining it as a constant but it’s value changes during script execution. Implementing it as a class would mean I’d have to rebuild the complete application from scratch :S

thanks!

Answer 1

I do not think you can do this using “pure” “real” arrays.

One way to get to this might be using some class that implements ArrayInterface ; you code would look like it’s using arrays… But it would actually be using objects, with accessor methods that could forbid write-access to some data, I guess…

It would have you change a couple of things (creating a class, instanciating it) ; but not everything : access would still be using an array-like syntax.

Something like this might do the trick (adapted from the manual) :

class obj implements arrayaccess {
    private $container = array();
    public function __construct() {
        $this->container = array(
            "one"   => 1,
            "two"   => 2,
            "three" => 3,
        );
    }
    public function offsetSet($offset, $value) {
        if ($offset == 'one') {
            throw new Exception('not allowed : ' . $offset);
        }
        $this->container[$offset] = $value;
    }
    public function offsetExists($offset) {
        return isset($this->container[$offset]);
    }
    public function offsetUnset($offset) {
        unset($this->container[$offset]);
    }
    public function offsetGet($offset) {
        return isset($this->container[$offset]) ? $this->container[$offset] : null;
    }
}


$a = new obj();

$a['two'] = 'glop'; // OK
var_dump($a['two']); // string 'glop' (length=4)

$a['one'] = 'boum'; // Exception: not allowed : one

You have to instanciate an object with new, which is not very array-like… But, after that, you can use it as an array.

And when trying to write to an “locked” property, you can throw an Exception, or something like that — btw, declaring a new Exception class, like ForbiddenWriteException, would be better : would allow to catch those specifically 🙂