深入函数.迭代器

1.迭代器只不过是一个实现迭代器协议的容器对象

2.自定义类如果定义了__iter__(self)(必须返回self)和next(self)方法,则实例化时检测到__iter__(self)返回self,迭代时候会自动调用对象的next方法返回

# -*- coding: utf-8 -*-
"""
#
# Authors: limanman
# OsChina: http://my.oschina.net/pydevops/
# Purpose:
#
"""


class FibonacciIteration(object):
    """Iteration class

    Attributes :
        cur_num: cur number if fibonaccis
        pre_num: first number
        nxt_num: second number
        fbs_num: max number of fibonaccis
    """

    def __init__(self, fbs_num):
        self.cur_num = 0
        self.pre_num = 0
        self.nxt_num = 1
        self.fbs_num = fbs_num

    def __iter__(self):
        return self

    def next(self):
        """Iteration next item."""
        while True:
            if self.cur_num > self.fbs_num:
                raise StopIteration
            (self.pre_num, self.nxt_num) = (self.nxt_num,
                                            self.pre_num + self.nxt_num)
            self.cur_num += 1
            return self.nxt_num

if __name__ == '__main__':
    for fb in FibonacciIteration(10):
        print fb