public function setExtension($extension) {

		if(false === is_string($extension)) {
			return trigger_error(sprintf('Argument 1 passed to %s() must be of the type string, "%s" given', __METHOD__, gettype($extension)), E_USER_ERROR);
		}

		//Prepend dot for extension if necessary
		$extension = ($extension[0] === '.') ? $extension : '.' . $extension;
		
		$this -> extension = $extension;

		return $this;
	}