Finish processing the data neatly, save the state and exit by pressing Ctrl-C (Python CLI)

interrupt_processing_data.py

from signal import SIGINT, signal
from time import sleep
import pickle


def load(store):
    try:
        with open(store, 'br') as f:
            start = pickle.load(f)
    except Exception:
        start = None
    return start


def dump(data, store):
    try:
        with open(store, 'wb') as f:
            pickle.dump(next(data), f)
    except Exception:
        with open(store, 'wb') as f:
            pickle.dump(None, f)
    

def source(start=None):
    '''Mock data source'''
    if start is None:
        start = 0
    yield from range(start, 30)

    
def process(data):
    '''Mock process'''
    sleep(1); print(data)

    
def trap_sigint(sig, frame):
    if input(' Break? [y]es, [N]o').startswith('y'):
        global save_and_exit
        save_and_exit = True
        

def main(store='saved_data'):
    ...
    data = source(load(store))
    global save_and_exit
    save_and_exit = False
    try:
        _ = signal(SIGINT, trap_sigint)
        print('Press Ctrl-C to stop.')
        while not save_and_exit:
            process(next(data))
    except StopIteration:
        dump(None, store) 
    else:
        dump(data, store)
    finally:
        signal(SIGINT, _)
    ...


main()