Python 实现 first()

zltzlt

Python 实现 first()

上代码：

_def = object()    # default value


def first(iterable, *, default=_def):
    """first(iterable, *, default) --> The first item of *iterable*, or *default* if *iterable* is empty"""
    for i in iterable:
        return i
    if default is _def:    # no default value was provided
        raise ValueError('first() was called on an empty iterable, and no default value was provided.')
    return default


print(first([3, 4, 6, 7]))     # Out 3
print(first(range(5, 8)))      # Out 5
print(first([], default=0))    # Out 0
print(first(()))               # Error

如果代码有问题，欢迎在评论区指正

永恒的蓝色梦想

这个是真的有点秀