public function __construct($sdir, $tdir, $sfile, $tfile)
{
$source = $sdir . DIRECTORY_SEPARATOR . $sfile . '.template';
if (file_exists($source)) {
$this->_source = $source;
} else {
throw new Components_Exception("No template at {$source}!");
}
$this->_target = $tdir . DIRECTORY_SEPARATOR . $tfile;
}