"""File:      sort_by_len_drv.py
   Purpose:   Driver for sort_by_length function

   Run:       python sort_by_len_drv.py

   Input:     List of words, one per line.
              Carriage return at beginning of line to end input

   Output:    The input list sorted from shortest to longest
"""

#----------------------------------------------------------------------
def sort_by_length(word_list):
   """Sort the words in word_list in order of increasing length
      This is a slight modification of a function in Section
      12.7 of Allen Downey, Python for Software Design"""

   t_list = []
   for word in word_list:
      t_list.append((len(word), word))

   t_list.sort()

   new_list = []
   for length, word in t_list:
      new_list.append(word)
   return new_list

#----------------------------------------------------------------------
def enter_word_list():
   """Read a list of words, one per line"""
   print "Enter a list of words, one per line"
   print "Hit enter at the beginning of a line to stop"
   wlist = []
   word = raw_input()
   while word != '':
      wlist.append(word)
      word = raw_input()

   return wlist

#----------------------------------------------------------------------
def print_word_list(wlist):
   """Print a list of words, one per line"""
   print "The words are:"
   for w in wlist:
      print "  ", w

#----------------------------------------------------------------------
if __name__ == "__main__":
   word_list = enter_word_list()
   new_list = sort_by_length(word_list)
   print_word_list(new_list)