[Tutor] _next

[Roel Schroeven]

Christopher Spears schreef:
> How does this script work?
> 
> #!/usr/bin/python
> 
> class IteratorExample:
>     def __init__(self, s):
>         self.s = s
>         self.next = self._next().next
>         self.exhausted = 0
>     def _next(self):
>         if not self.exhausted:
>             flag = 0
>             for x in self.s:
>                 if flag:
>                     flag = 0
>                     yield x
>                 else:
>                     flag = 1
>             self.exhausted = 1
>     def __iter__(self):
>         return self._next()

I always use generator functions like this to achieve the same effect:

def IteratorExample():
     flag = 0
     for x in s:
         if flag:
             flag = 0
             yield x
         else:
             flag = 1

Much less boilerplate and behind-the-scenes bookkeeping, so it's easier 
to type and understand. Result is the same:

 >>> a = IteratorExample('edcba')
 >>> for x in a:
	print x

	
d
b

 >>> a = IteratorExample('edcba')
 >>> print a.next()
d
 >>> print a.next()
b
 >>> print a.next()

Traceback (most recent call last):
   File "<pyshell#82>", line 1, in -toplevel-
     print a.next()
StopIteration



-- 
If I have been able to see further, it was only because I stood
on the shoulders of giants.  -- Isaac Newton

Roel Schroeven