code: def getAllPars(self, sddsfile=None):
          
          if SDDS_:
              if sddsfile is not None:
                  sddsobj = sdds.SDDS(2)
                  sddsobj.load(sddsfile)
              else:
                  sddsobj = self.sddsobj
              return sddsobj.parameterName
          else:
              if sddsfile is None:
                  sddsfile = self.sddsfile
              return subprocess.check_output(['sddsquery', '-par', sddsfile]).split()
docs: get all available parameter names from sddsfile
  
          :param sddsfile: sdds file name, if not given, rollback to the one that from ``__init__()``
          :return: all sdds data parameter names
          :rtype: list
  
          .. warning:: `sdds` needs to be installed as an extra dependency.
  
          :Example:
  
          >>> dh = DataExtracter('test.w1')
          >>> print(dh.getAllPars())
          ['Step', 'pCentral', 'Charge', 'Particles', 'IDSlotsPerBunch', 'SVNVersion', 'Pass', 'PassLength',
           'PassCentralTime', 'ElapsedCoreTime', 'MemoryUsage', 's', 'Description', 'PreviousElementName']
  
          :seealso: :func:`getAllCols`