code: public function write($encoding)
      {
          if (! file_exists($this->getValue())) {
              return;
          }
          $encoding->attach(
                  $this->getName(),
                  implode('', file($this->getValue())),
                  basename($this->getValue()));
      }
docs: Dispatches the value into the form encoded packet.
  
  @param SimpleEncoding $encoding    Form packet.