What is the difference between an iterator and an iterable?
---
I will try to be concise: an iterator has a __next__ method for "inch
worming" forward
(from yield to yield internally, if defined by a generator function, but
only some iterators are).
Iterables, if they have an __iter__ method, should give rise to an iterator
by that method.
However, even something so dumb as a class with just __getitem__ can be
treated as an
iterable. Let's see:
class Dumb:
"""uber primitive"""
def __init__(self, it):
self.thelist = it
def __getitem__(self, n):
return self.thelist[n]
obj = Dumb(list("mary had a little lamb"))
for d in obj: # iterables will work here
print(d, end="")
print()
# can we use it with iter() ?
theiter = iter(obj)
if "__next__" in dir(theiter):
print("wow, we have a grown up iterator!")
for i in range(4):
print(next(theiter))
Output:
mary had a little lamb
wow, we have a grown up iterator!
m
a
r
y
===
Kirby Urner
Senior Python Mentor
Python Track / OST
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