method.php

<?php

class v1_user extends \Pickles\Resource
{
    /**
     * Has to be broken out by request method as to not cause fall out. The other
     * option could be to grab all of the method names, loop through and look for 
     * the largest revision number (if the revision is not specified and _METHOD()
     * doesn't exist
     **/

    private $get_latest = 20141011;

    public function GET_20140101()
    {
        // ...
    }
    
    public function GET_20140101()
    {
        // ...
    }
    
    public function GET_20141011()
    {
        // latest...
    }
}

switch.php

<?php

class v1_user extends \Pickles\Resource
{
    public function GET()
    {
        switch ($revision)
        {
            case 20140101:
                // ...
                break;
                
            case 20140601:
                // ...
                break;
                
            case 20141011:
            default:
                // latest...
                break;
        }
    }
}