python - Is there an iter which accepts a complex sentinel? -

i use iter 2 arguments , wondering if there equivalent accept more complex sentinel?

as example, in code below

# returns digits 1 10 upon subsequently calling .create(),  # returns 'end' each time afterwards class myclass:     def __init__(self):         self.counter = 0     def create(self):         self.counter += 1         if self.counter > 10:             return 'end'         else:             return self.counter  c = myclass() in iter(c.create, 'end'):     print(i) 

the iteration ends upon getting 'end'. have end after getting, say, total of 2 'end' (not 1 after other - code above generate 'end' after first ten calls 1 can imagine case interlaced other values).

in essence, looking way use more complex sentinel. there such concept?

i know can resort obvious-but-ugly code mentioned in previous question, hovewer @happyleapsecond answer elegant keep spirit (i went though itertools none of available methods seem job)

you use itertools.takewhile stateful predicate. example:

>>> itertools import takewhile >>> def create_predicate(func, max_count):     """return false when func evaluates true max_count time."""     def predicate(elem):         if func(elem):             predicate.count += 1         if predicate.count == max_count:             return false         return true     predicate.count = 0     return predicate  >>> list(takewhile(create_predicate(lambda elem: elem % 3 == 0, 3), range(1, 20))) [1, 2, 3, 4, 5, 6, 7, 8] 

in example above, create_predicate(lambda elem: elem % 3 == 0, 3) creates complex predicate function stop iteration on third multiple of three. in case,

i have end after getting, say, total of 2 'end'

you use create_predicate(lambda elem: elem == 'end', 2).