============================
 Build Your Acl Driver
============================
Creating a custom ACL driver involves a few steps that should feel like a relatively easy task for a PHP programmer.  Basically, your new driver needs to implement the only abstract class defined in the ``ACL.php`` file, that is ``org_geoprisma_acl_ACL`` and its abstract public function ``isAuthorized``.  Once defined, you then set GeoPrisma to use your new driver.

See the ``BorealisACL`` or ``NoACL`` driver for an example.

1. Create a new PHP class which extends ``org_geoprisma_acl_ACL``

   .. code-block:: php
    
    <?php

    class your_custom_acl_driver extends org_geoprisma_acl_ACL
    {
       ....
    }
    
    ?>

2. Implement the ``com_borealis_foundation_util_Singleton`` abstract function in the constructor of your new class.    

   .. code-block:: php
    
    <?php

    class your_custom_acl_driver extends org_geoprisma_acl_ACL
    {
        private static $s_objInstance = null;

        private function __construct()
        {
            // Singleton DP
        }

        public static function getInstance()
        {
            if (is_null(self::$s_objInstance))
            {
                self::$s_objInstance = new your_custom_acl_driver();
            }
            return self::$s_objInstance;
        }

    }
    
    ?>
    
3. Implement the ``isAuthorized`` function in your class.  This function receives two parameters : ``Ressource Name`` and ``Action Name``.  Your function checks if the action in this resource is authorized and returns true or false.    

   .. code-block:: php
    
    <?php

    class your_custom_acl_driver extends org_geoprisma_acl_ACL
    {
        public function isAuthorized($pstrRessource, $pstrAction)
        {
            ....
               return true;
            ....
               return false;
        }
    }
    
    ?>

4. Set Geoprisma to use your driver [#ACLSetter]_



   .. code-block:: php
    
    <?php

    org_geoprisma_SettingImpl::setACLClass('your_custom_acl_driver'); 
    
    ?>

   P.S: Your driver class needs to be loaded before, or loaded in an autoload function like com_borealis_Autoload.php   
    
   .. code-block:: php
    
    <?php

    require 'your_custom_acl_driver.php'
    
    ?>

5. Final result of your_custom_acl_driver.php
    
   .. code-block:: php
    
    <?php

    class your_custom_acl_driver extends org_geoprisma_acl_ACL
    {
        private static $s_objInstance = null;

        private function __construct()
        {
            // Singleton DP
        }

        public static function getInstance()
        {
            if (is_null(self::$s_objInstance))
            {
                self::$s_objInstance = new your_custom_acl_driver();
            }
            return self::$s_objInstance;
        }

        public function isAuthorized($pstrRessource, $pstrAction)
        {
            ....
               return true;
            ....
               return false;
        }
    }
    
    ?>

.. [#ACLSetter] The default acl driver used is defined in the ``Setting.php`` file.  It defaults to ``org_geoprisma_acl_NoACL``.  The implementation resides in the ``SettingImpl.php`` class.  That class defines getters and setters, amongst which the setter for the locale driver : ``setACLClass``.  This is usually done in the ``common.php`` file.