Stopping an iteration without using `break` in Python 3

Question

For example, can this code be rewritten without break (and without continue or return)?

import logging

for i, x in en         


        

Answer 1

You could use a boolean value to check if you are done. It will still iterate the rest of the loop but not execute the code. When it is done it will continue on its way without a break. Example Pseudo code below.

doneLogging = False
for i, x in enumerate(x):
    if not doneLogging:
        logging.info("Processing `x` n.%s...", i)
        y = do_something(x)
        if y == A:
            logging.info("Doing something else...")
            do_something_else(x)
        elif y == B:
            logging.info("Done.")
            doneLogging = True

Answer 2

You could always use a function and return from it:

import logging

def func():
    for i, x in enumerate(x):
        logging.info("Processing `x` n.%s...", i)
        y = do_something(x)
        if y == A:
            logging.info("Doing something else...")
            do_something_else(x)
        elif y == B:
            logging.info("Done.")
            return # Exit the function and stop the loop in the process.
func()

Although using break is more elegant in my opinion because it makes your intent clearer.

Answer 3

You can also use sys.exit()

import logging
import sys

for i, x in enumerate(x):
    logging.info("Processing `x` n.%s...", i)
    y = do_something(x)
    if y == A:
        logging.info("Doing something else...")
        do_something_else(x)
    elif y == B:
        logging.info("Done.")
        sys.exit(0)

Answer 4

The break and continue keywords only have meaning inside a loop, elsewhere they are an error.

for grooble in spastic():
    if hasattr(grooble, '_done_'):
        # no need for futher processing of this element
        continue
    elif grooble is TheWinner:
        # we have a winner!  we're done!
        break
    else:
        # process this grooble's moves
        ...

Anyone who says break and continue should not be used is not teaching good Python.