不，没有这样的方法。迭代的结束由异常表示。请参见文档。

在任意迭代器对象中尝试__length_hint__()方法:

iter(...).__length_hint__() > 0

也许只有我这么想，但虽然我喜欢https://stackoverflow.com/users/95810/alex-martelli的答案，但我发现这个更容易读:

from collections.abc import Iterator  # since python 3.3 Iterator is here

class MyIterator(Iterator):  # need to subclass Iterator rather than object
  def __init__(self, it):
    self._iter = iter(it)
    self._sentinel = object()
    self._next = next(self._iter, self._sentinel)
    
  def __iter__(self): 
    return self
  
  def __next__(self):        # __next__ vs next in python 2
    if not self.has_next():
      next(self._iter)  # raises StopIteration

    val = self._next
    self._next = next(self._iter, self._sentinel)
    return val
  
  def has_next(self):
    return self._next is not self._sentinel

非常有趣的问题，但是这个“hasnext”的设计已经放进了leetcode: https://leetcode.com/problems/iterator-for-combination/

这是我的实现:

class CombinationIterator:

def __init__(self, characters: str, combinationLength: int):
    from itertools import combinations
    from collections import deque
    self.iter = combinations(characters, combinationLength)
    self.res = deque()


def next(self) -> str:
    if len(self.res) == 0:
        return ''.join(next(self.iter))
    else:
        return ''.join(self.res.pop())


def hasNext(self) -> bool:
    try:
        self.res.insert(0, next(self.iter))
        return True
    except:
        return len(self.res) > 0

hasNext在某种程度上转换为StopIteration异常，例如:

>>> it = iter("hello")
>>> it.next()
'h'
>>> it.next()
'e'
>>> it.next()
'l'
>>> it.next()
'l'
>>> it.next()
'o'
>>> it.next()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
StopIteration

StopIteration文档:http://docs.python.org/library/exceptions.html#exceptions.StopIteration 一些关于python中的迭代器和生成器的文章:http://www.ibm.com/developerworks/library/l-pycon.html

使用“for”可以实现他自己版本的“next”避免异常

def my_next(it):
    for x in it:
        return x
    return None