Description:
------------
Since http://bugs.php.net/bug.php?id=39466 was shot down, PHP is in need of a method to which we can set class member variables as read-only during runtime to prevent changing of values that are critically important for script execution.

I would like to use a class constant for this but, because it cannot be assigned a value at runtime, it is impossible to do so. The reproduce code is an example of a value that I would like to set as read only. The scope of the variable should not matter in this suggestion as it is practical that it would need to be changed given a proper reason.

Reproduce code:
---------------
<?php
class parser
{
    public $magic_quotes = false;

    public __construct()
    {
        //Add some sort of identifier here to set the
        //value read only
        (readonly)$this->magic_quotes = (bool)get_magic_quotes_gpc();
    }

    public my_stripslashes( $str )
    {
         if( self::magic_quotes === true )
         {
             $str = stripslashes( $str );
         }
         return $str;
    }

    public change_magic_quotes($to)
    {
         $this->magic_quotes = $to;
    }
}

$parser = new parser();

//Returns stripped string
$stripped = $parser->my_stripslashes( 'Hi, there\'s a coke in the fridge' );

//Doesn't change the value of magic_quotes and flags an
//E_WARNING or E_NOTICE error.
$parser->change_magic_quotes( true );
?>

Expected result:
----------------
Hope to have it not allow the variable to be changed (ha, a constant, what a silly notion) and pop an error of some kind to the parser.

Actual result:
--------------
Not implemented, thus values can be changed at any time as long as the variable is within the visibility scope of calling party.