/**
  * Short description of method getValue
  *
  * @access public
  * @author Joel Bout, <*****@*****.**>
  * @param  Resource resource
  * @param  Column column
  * @return string
  */
 public function getValue(core_kernel_classes_Resource $resource, tao_models_classes_table_Column $column)
 {
     $returnValue = array();
     $vcUri = $column->getVariableClass()->getUri();
     if (isset($this->cache[$vcUri][$resource->getUri()][$column->getContextIdentifier() . $column->getIdentifier()])) {
         $returnValue = $this->cache[$vcUri][$resource->getUri()][$column->getContextIdentifier() . $column->getIdentifier()];
     } else {
         common_Logger::d('no data for resource: ' . $resource->getUri() . ' column: ' . $column->getIdentifier());
     }
     return $returnValue;
 }