python - Creating a function which reverses iterator -

i'm doing in attempt better understand iter() , next() methods better.

so understand can done using built-ins:

>>>animal = 'cat' >>>print(list(reversed(animal))) ['t','a','c'] 

but can done creating class iterable:

class reverselist():     def __init__(self, data):         self.data = data         self.index = len(data)      def __iter__(self):         return self      def __next__(self):         if self.index == 0:             raise stopiteration         self.index =self.index -1         return self.data[self.index]      def intolist(self):         self.test = [i in self]         return self.test  rev = reverselist('cat') print(rev.intolist())  ['t','a','c'] 

however, i'm having trouble doing same thing using functions instead of going ooo route.

is there way functions using iter() , next() methods without having resort comprehensions , loops?

you can generator function:

def reverse_list(seq):     index in range(len(seq)-1, -1, -1):         yield seq[index] 

calling function produce "generator object" supports iter() , next().

>>> rev = reverse_list('cat') >>> rev <generator object reverse_list @ 0x10a93ebe0> >>> next(rev) 't'