HMVC loading driver across modules

Have the following (simplified) setup:

/modules/backend/libraries/Queue/Queue.php
/modules/backend/libraries/Queue/drivers/Queue_a.php
/modules/backend/libraries/Queue/drivers/Queue_b.php

/modules/admin/controllers/Test.php

Am attempting to use Queue driver library inside of Test controller - ie across modules.
The basic load of driver library works, but the driver library is unable to find/load its child drivers/drivername.


This works in Test.php if Queue::add is a stub (ie not doing anything)

PHP Code:

function test()
{
   $this->load->library('backend/queue','queue');
   $this->queue->add('test message');
} 


But, when the library then tries to load an individual driver (e.g. to add an item into a queue), the load fails: (in Queue/Queue.php)

PHP Code:

function add($payload='')
{
   //...ignore code that picks which driver to use - assume its queue_a
   $this->queue_a->add_message($payload); //this fails, Queue_a.php cannot be found to load
} 


The problem seems to be that HMVC overrides the core Loader.php file - but the code in core/libraries/Driver.php that locates individual driver child classes is not HMVC aware, and does not use the Loader class.

My first thought for solution is to extend core/libraries/Driver.php in new file MX_Driver.php:

PHP Code:

public function __get($child)
{
    //establish path of child driver     
    $lib_name = get_class($this);
    $reflector = new ReflectionClass($lib_name);
    $class_path =  dirname($reflector->getFileName());
    $lib_path = dirname($class_path);
    $module_path = dirname($lib_path);

    //temp add the path for CI loader to find
    $this->CI->load->add_package_path($module_path);
    // Try to load the driver
    return $this->load_driver($child);
    // Reset things to clean up
    $this->load->remove_package_path($module_path);
} 


Have a feeling this has been solved before however?

I had this problem too, put the method below to your main driver file!
This will override the default driver loading method.

PHP Code:

public function load_driver($child)
{
    // Get CodeIgniter instance and subclass prefix
    $prefix = config_item('subclass_prefix');

    if ( ! isset($this->lib_name))
    {
        // Get library name without any prefix
        $this->lib_name = str_replace(array('CI_', $prefix), '', get_class($this));
    }

    // The child will be prefixed with the parent lib
    $child_name = $this->lib_name.'_'.$child;

    // See if requested child is a valid driver
    if ( ! in_array($child, $this->valid_drivers))
    {
        // The requested driver isn't valid!
        $msg = 'Invalid driver requested: '.$child_name;
        log_message('error', $msg);
        show_error($msg);
    }

    // Search the child only in the current folder...
    $path = realpath(dirname(__FILE__));

    // Does the file exist?
    $file = $path . '/drivers/' . $child_name . '.php';
    if (file_exists($file))
    {
        // Include source
        include_once($file);
    }

    if (class_exists($child_name, FALSE))
    {
        $class_name = $child_name;
    }
    else
    {
        $msg = 'Unable to load the requested driver: '.$class_name;
        log_message('error', $msg);
        show_error($msg);
    }

    // Instantiate, decorate and add child
    $obj = new $class_name();
    $obj->decorate($this);
    $this->$child = $obj;
    return $this->$child;
} 


Its interesting that the default CI driver->load($child) method goes looking in all Package paths, when a child driver by convention lives in sub-directory of the parent. I can see your code resolves that neatly.

I simply altered the shorter __get($child) magic method because there is less code to override - so less chance of clash with future CI changes. I guess HMCV already changes a lot of core code anyhow and this risks that load($child) calls still fail.

Another small change I needed to make  - from line 196 of third_party/MX/Modules.php - to load drivers/libraries across modules:

PHP Code:

foreach($modules as $module => $subpath) 
{            
    $fullpath = $location.$module.'/'.$base.$subpath;

    if ($base == 'libraries/' OR $base == 'models/')
    {
        if(is_file($fullpath.ucfirst($file_ext))) return array($fullpath, ucfirst($file));
        /*
         * EDITS
         * check for drivers loaded across modules in a subdir with same name as file
         * the core library loader does the same trick, but MX one does not
         */
        else if($base == 'libraries/')
        {
                $fullpath = $fullpath.ucfirst($file).'/'; //file here is /classname
                if(is_file($fullpath.ucfirst($file_ext))) return array($fullpath, ucfirst($file));
        }
        /*
         * END EDIT
         */
    }
    else
    /* load non-class files */
    if (is_file($fullpath.$file_ext)) return array($fullpath, $file);
} 


This allows me to load a driver with $this->load('module/driver') across modules as shown in the code above.

For future reference: Note there are two possible errors in the code posted by Orionstar above:

Line 60:

PHP Code:

$msg = 'Unable to load the requested driver: '.$class_name; 


At that point $class_name is not defined, should be $child.

Also, in line 44

Code:

$path = realpath(dirname(__FILE__));

__FILE__ refers to the directory location of Class where the function is defined, ie the parent - not of the class that inherits the definition.
This can be solved with:

PHP Code:

$c = new ReflectionClass($this);
$path = realpath(dirname($c->getFileName())); 


Thank you to point out the mistakes in the code.