How to create a spinning command line cursor?

Something like this, assuming your terminal handles \b

import sysimport timedef spinning_cursor():    while True:        for cursor in '|/-\\':            yield cursorspinner = spinning_cursor()for _ in range(50):    sys.stdout.write(next(spinner))    sys.stdout.flush()    time.sleep(0.1)    sys.stdout.write('\b')

Easy to use API (this will run the spinner in a separate thread):

import sysimport timeimport threadingclass Spinner:    busy = False    delay = 0.1    @staticmethod    def spinning_cursor():        while 1:             for cursor in '|/-\\': yield cursor    def __init__(self, delay=None):        self.spinner_generator = self.spinning_cursor()        if delay and float(delay): self.delay = delay    def spinner_task(self):        while self.busy:            sys.stdout.write(next(self.spinner_generator))            sys.stdout.flush()            time.sleep(self.delay)            sys.stdout.write('\b')            sys.stdout.flush()    def __enter__(self):        self.busy = True        threading.Thread(target=self.spinner_task).start()    def __exit__(self, exception, value, tb):        self.busy = False        time.sleep(self.delay)        if exception is not None:            return False

Now use it in a with block anywhere in the code:

with Spinner():  # ... some long-running operations  # time.sleep(3) 

A nice pythonic way is to use itertools.cycle:

import itertools, sysspinner = itertools.cycle(['-', '/', '|', '\\'])while True:    sys.stdout.write(next(spinner))   # write the next character    sys.stdout.flush()                # flush stdout buffer (actual character display)    sys.stdout.write('\b')            # erase the last written char

Also, you might want to use threading to display the spinner during a long function call, as in http://www.interclasse.com/scripts/spin.php