Python getslice项运算符重写函数不工作

练习为学习Python OOP而发布的示例。我正在寻找“1到4”的输出，但它会抛出下面的错误

class FakeList:
     def __getslice___(self,start,end):
         return str(start) + " to " + str(end)

f = FakeList()

f[1:4]

注意：使用

f.\uuuu getitem\uuuu（1，4）

会得到正确的输出--“1到4”，如上面的链接所示

回溯（最近的呼叫） 最后）在（） ---->1F[1:4]

TypeError:“FakeList”对象不可下标

---

如注释中所述，

\uu getitem\uuu

方法采用一个

slice

类型的参数，您可以通过

slice.start

和

slice.stop

访问范围的开始/结束，下面是一个示例，其中包含一些调试输出，以显示发生了什么：

class FakeList:

    def __getitem__(self, slice_):
         print('slice_', slice_)
         print('type(slice_)', type(slice_))
         print('dir(slice_)', dir(slice_))
         return str(slice_.start) + " to " + str(slice_.stop)

f = FakeList()

print(f[1:4])

输出：

slice_ slice(1, 4, None)

type(slice_) <class 'slice'>

dir(slice_) ['__class__', '__delattr__', '__dir__', '__doc__',
'__eq__', '__format__', '__ge__', '__getattribute__', '__gt__',
'__hash__', '__init__', '__le__', '__lt__', '__ne__', '__new__',
'__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__',
'__str__', '__subclasshook__', 'indices', 'start', 'step', 'stop']

1 to 4

slice\uuslice（1，4，无）
类型（切片）
目录（切片）['''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''，
“\uuuuuu eq\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu，
"散列","初始化","列","列","列","新",，
"减少","减少","增加","报告","设置属性","大小",，
“\uuuu str\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu
1至4

什么是Python版本？不要使用

\uu getslice\uu

，它早就被弃用并在Python 3中删除了。使用

\uuuuuuu getitem\uuuuuuuu

，它支持切片对象。使用“getitem”代替still会导致错误。使用“getitem”时，新的错误为：“TypeError:\uuuuuuuuu getitem\uuuuuu（）缺少1个必需的位置参数：'end'”