def __init__(self, filename):
    """Create a workspace reader/writer.

    :param filename: (str)

    """
    self.__filename = u(filename)

@staticmethod
def default_extension():
    """Return the default extension to read/write workspaces."""
    return sppasWJSON().default_extension

@staticmethod
def extensions():
    """Return the list of supported extensions in lower case."""
    return list(sppasWkpRW.WORKSPACE_TYPES.keys())

def read(self):
    """Read a workspace from a file.

        :returns: (sppasWkpRW)

        """
    try:
        wkp = sppasWkpRW.create_wkp_from_extension(self.__filename)
        wkp.read(self.__filename)
    except Exception:
        raise
    return wkp

@staticmethod
def create_wkp_from_extension(filename):
    """Return a workspace according to a filename.

        :param filename: (str)
        :returns: sppasBaseWkpIO()

        """
    extension = os.path.splitext(filename)[1][1:]
    extension = extension.lower()
    if extension in sppasWkpRW.extensions():
        return sppasWkpRW.WORKSPACE_TYPES[extension]()
    raise IOExtensionError(filename)

def write(self, wkp):
    """Write a workspace into a file.

        :param wkp: (sppasWorkspace) Data to be saved

        """
    wkp_rw = sppasWkpRW.create_wkp_from_extension(self.__filename)
    wkp_rw.set(wkp)
    try:
        wkp_rw.write(self.__filename)
    except UnicodeDecodeError as e:
        raise AioEncodingError(self.__filename, str(e))
    except Exception:
        raise
    return wkp_rw