gflags.py 文件源码

def GetHelpWidth():
  """Returns: an integer, the width of help lines that is used in TextWrap."""
  if (not sys.stdout.isatty()) or (termios is None) or (fcntl is None):
    return _help_width
  try:
    data = fcntl.ioctl(sys.stdout, termios.TIOCGWINSZ, '1234')
    columns = struct.unpack('hh', data)[1]
    # Emacs mode returns 0.
    # Here we assume that any value below 40 is unreasonable
    if columns >= 40:
      return columns
    # Returning an int as default is fine, int(int) just return the int.
    return int(os.getenv('COLUMNS', _help_width))

  except (TypeError, IOError, struct.error):
    return _help_width