breaking out of nested loop

[Steven D'Aprano]

On Tue, 12 Jul 2005 10:19:04 -0400, rbt wrote:

> What is the appropriate way to break out of this while loop if the for
> loop finds a match?

Refactor it into something easier to comprehend?

And comments never go astray.


(Untested. And my docstrings are obviously bogus.)

def make_one_thing(group, x):
    """Makes a thing by plonking the frobber.
    Expects group to be a list of foo and x to be an index.
    """
    mix = random.sample(group, x)
    make_string = ''.join(mix)
    n = md5.new(make_string)
    match = n.hexdigest()
    return match
    
def group_matches(group, target):
    """Cycles over a group of foos, plonking the frobber of each
    item in turn, and stopping when one equals target.
    """
    for x in xrange(len(group)):
        try:
            match = make_one_thing(group, x)
            if match == target:
                return True
        except Exception, e:
            # don't stop just because the program has a bug
            print e
    # if we get here, there was no successful match after the 
    # entire for loop
    return False

def test_until_success:
    """Loop forever, or until success, whichever comes first.
    """
    group = [1, 2, 3, 4]
    target = 5
    flag = False
    while not flag:
        print "No matches yet, starting to search..."
        flag = group_matches(group, target)
    # if we ever get here, it means we found a collision, and
    # flag became True, so the while loop just dropped out
    print "Collision!!!"
    stop = time.strftime("%H:%M:%S-%m-%d-%y", time.localtime())
    print "Stopped at", stop



-- 
Steven.