我怎么知道发电机一开始是否空了？

Question

有没有一种简单的方法可以测试生成器是否没有任何东西，例如peek，hasNext，isEmpty等？

Answer 1

建议：def peek(iterable):    try:        first = next(iterable)    except StopIteration:        return None    return first, itertools.chain([first], iterable)用法：res = peek(mysequence)if res is None:    # sequence is empty.  Do stuff.else:    first, mysequence = res    # Do something with first, maybe?    # Then iterate over the sequence:    for element in mysequence:        # etc.