为我的自定义迭代器实现iteritems函数？

Question

以下程序的目的是学习python生成器和迭代器实现,以便了解Python魔术方法.

我卡住了实现这个iteritems()功能.另外,我想知道我是否朝着正确的方向前进,或者在理解python魔术方法时我在概念上是错误的.

import random

class Random(object):
    """ generate randomised int of specified length --> [r1, r2, r3....] """

    def __init__(self, length = 1, rand_range = 100):
        self.index = 0
        self.generated_range = []
        self.length = length if str(length).isdigit() else 1
        self.rand_range = rand_range if str(rand_range).isdigit() else 100

    def __iter__(self): return self

    def next(self):
        if self.index < self.length:
            item = random.randrange(0, self.rand_range)
            self.generated_range.append(item)
            self.index += 1
            return item
        raise StopIteration

    def __eq__(self, obj):
        if self.length == obj.length and self.rand_range == obj.rand_range:
            return True
        return False

    def __len__(self):
        return self.length

    def __contains__(self, item):
        if not self.index == self.length:
            while self.next(): continue
        if item in self.generated_range:
            return True
        return False

    def __getitem__(self, key):
        if key in self.generated_range:
            return key * 100
        raise KeyError

    def __setitem__(self, key, value):
        raise NotImplemented

    def __delitem__(self, key):
        raise NotImplemented

    def iteritems(self):
        if not self.index == self.length:
            while self.next(): continue
        for item in self.generated_range:
            yield item

if __name__ == '__main__':
    r1 = Random(10)
    print [ r for r in r1]
    print 10 in r1
    r2 = Random(20)
    print r2.iteritems()

CodePAD链接

Answer 1

iteritems应该返回字典的 (key, val) 对序列，所以我认为它不适合您的课程。如果您创建了 UserDict 的后代，那么可能会出现覆盖它的情况。

如果您确实要覆盖 iteritems，则应该通过生成键、值对来实现。

可怜的程序员的重写：

def iteritems(self):
    return iter([(x[0], x) for x in "alpha bravo charlie".split()])