你想要一个

slice() object：

index = slice(0, 2)

print(somelist[index])

slice()模拟您可以在[start：stop：stride]预订语法中指定的start,stop和stride值作为对象.

从文档：

Return a 07001 object representing the set of indices specified by range(start, stop, step). The start and step arguments default to None. Slice objects have read-only data attributes start, stop and step which merely return the argument values (or their default).

在幕后,Python实际上在调用自定义__getitem__方法时将订阅转换为slice()对象：

>>> class Foo(object):

... def __getitem__(self, item):

... return item

...

>>> Foo()[42:81:7]

slice(42, 81, 7)

>>> Foo()[:42]

slice(None, 42, None)

一个可行的替代方案是将start和stop存储为单独的值：

startindex = 0

stopindex = 2

print(somelist[start:stop])