The Iterator Protocol
An iterator must implement two methods: __iter__() (returns self) and __next__() (returns the next value or raises StopIteration).
Python
Intermediate
4 min read
The Iterator Protocol
Example
class Counter:
def __init__(self, limit):
self.limit = limit
self.n = 0
def __iter__(self):
return self
def __next__(self):
if self.n >= self.limit:
raise StopIteration
self.n += 1
return self.n
for val in Counter(3):
print(val) # 1 2 3 Pro Tip
Implementing __iter__ on the iterator (returning self) allows it to be used directly in for loops.