Naming Loops in Python

Question

I recently read this question which had a solution about labeling loops in Java.

I am wondering if such a loop-naming system exists in Python. I have been in a situation multiple times where I do need to break out of an outer for loop from an inner for loop. Usually, I solve this problem by putting the inner loop in a function that returns (among others) a boolean which is used as a breaking condition. But labeling loops for breaking seems a lot simpler and I would like to try that, if such functionality exists in python

Does anyone know if it does?

Answer 1

Here's a way to break out of multiple, nested blocks using a context manager:

import contextlib  @contextlib.contextmanager def escapable():     class Escape(RuntimeError): pass     class Unblock(object):         def escape(self):             raise Escape()      try:         yield Unblock()     except Escape:         pass 

You can use it to break out of multiple loops:

with escapable() as a:     for i in xrange(30):         for j in xrange(30):             if i * j > 6:                 a.escape() 

And you can even nest them:

with escapable() as a:     for i in xrange(30):         with escapable() as b:             for j in xrange(30):                 if i * j == 12:                     b.escape()  # Break partway out                 if i * j == 40:                     a.escape()  # Break all the way out