# spinner_thread.py

# credits: Adapted from Michele Simionato's

# multiprocessing example in the python-list:

# https://mail.python.org/pipermail/python-list/2009-February/538048.html

# BEGIN SPINNER_THREAD

import threading

import itertools

import time

import sys

class Signal: # <1>

go = True

def spin(msg, signal): # <2>

write, flush = sys.stdout.write, sys.stdout.flush

for char in itertools.cycle('|/-\\'): # <3>

status = char + ' ' + msg

write(status)

flush()

write('\x08' * len(status)) # <4>

time.sleep(.1)

if not signal.go: # <5>

break

write(' ' * len(status) + '\x08' * len(status)) # <6>

def slow_function(): # <7>

# pretend waiting a long time for I/O

time.sleep(3) # <8>

return 42

def supervisor(): # <9>

signal = Signal()

spinner = threading.Thread(target=spin,

args=('thinking!', signal))

print('spinner object:', spinner) # <10>

spinner.start() # <11>

result = slow_function() # <12>

signal.go = False # <13>

spinner.join() # <14>

return result

def main():

result = supervisor() # <15>

print('Answer:', result)

if __name__ == '__main__':

main()

# END SPINNER_THREAD