python中如何创建一个迭代器

python中如何创建一个迭代器

迭代器的类必须包含两个方法;&nbsp__iter__()&nbspand&nbspnext().

下面是一个自定义的奇数迭代器

class OddIterator(object):
 
    def __init__(self):
        self.value = -1
 
    # Required for the for-in syntax
    def __iter__(self):
        return self
 
    # Returns the next value of the iterator
    def next(self):
        self.value += 2
        return self.value

测试迭代器的next方法

iter = OddIterator()
 
assert iter.next() == 1
assert iter.next() == 3
assert iter.next() == 5
assert iter.next() == 7

测试for&nbspin&nbsp语法是否正确

iter = OddIterator()
 
# Prints 1, 3, 5, 7 and 9
for i in iter:
    print i
    if i >= 9:
        break