函数形式实现
def my_range(start, end=None, step=1):
result = []
beg = None
if end == None:
beg = 0
final = start-1
else:
beg = start
if step >0:final = end-1
else: final = end+1
if step > 0:
while beg<=final:
yield beg
beg +=step
elif step < 0:
while final<=beg:
yield beg
beg +=step
else:
raise BaseException("step not allow 0")
for i in my_range(-1,-1):
print(i)
对象形式实现(你对象没了)
class MyRange:
def __init__(self, start, stop=None, step=None):
# 模拟range从0开始的行为
if stop is None:
self.start = 0
self.stop = start - 1
else:
self.start = start
self.stop = stop - 1
self.step = step
# 保留原始参数
self.origin_start = self.start
self.origin_stop = self.stop + 1
self.origin_step = self.step
def __repr__(self):
"""
:return: 显示表现
"""
if self.origin_step:
result = '{}({}, {}, {})'.format(
self.__class__.__name__,
self.origin_start,
self.origin_stop,
self.origin_step
)
else:
result = '{}({}, {})'.format(
self.__class__.__name__,
self.origin_start,
self.origin_stop
)
return result
def __iter__(self):
return self
def __next__(self):
"""
:return: 返回当前数字，然后在当前数字上+1
"""
result = self.start
if self.start <= self.stop:
self.start += 1
else:
raise StopIteration
return result
def __getitem__(self, item):
"""
:param item: 如果是单个数字, 那么item的类型将会是int,
如果是分片那么item将会是一个slice.
:return: 返回分片结果
"""
def is_index_error(_start):
if _start > self.stop:
raise IndexError('分片不得大于最大值.')
if isinstance(item, int):
result = self.origin_start + item
is_index_error(result)
elif isinstance(item, slice):
start = self.origin_start + item.start
stop = self.origin_start + item.stop
list(map(is_index_error, MyRange(start, stop)))
result = MyRange(start, stop)
else:
raise KeyError
return result
