[Tutor] _next

[Christopher Spears]

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()

def main():
    a = IteratorExample('edcba')
    for x in a:
        print x
    print '=' * 30
    a = IteratorExample('abcde')
    print a.next()
    print a.next()
    print a.next()
    print a.next()
    print a.next()
    print a.next()

if __name__ == '__main__':
    main()


Here is the output:

d
b
==============================
b
d
Traceback (most recent call last):
  File "./python_101_iterator_class.py", line 35, in ?
    main()
  File "./python_101_iterator_class.py", line 29, in
main
    print a.next()
StopIteration

I think a lot of my confusion comes from not
understanding what _next is.  I got this script from
an online tutorial at python.org.  Is there a better
way to write the script, so I can actually understand it?

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