Eric Nieuwland wrote:
> Travis Oliphant wrote:
>> PEP: ###
>> Title: Allowing any object to be used for slicing
>> [...]
>> Rationale
>>
>> Currently integers and long integers play a special role in slice
>> notation in that they are the only objects allowed in slice
>> syntax. In other words, if X is an object implementing the sequence
>> protocol, then X[obj1:obj2] is only valid if obj1 and obj2 are both
>> integers or long integers. There is no way for obj1 and obj2 to
>> tell Python that they could be reasonably used as indexes into a
>> sequence. This is an unnecessary limitation.
>> [...]
>
> I like the general idea from an academic point of view.
> Just one question: could you explain what I should expect from x[
> slicer('spam') : slicer('eggs') ] when slicer implements this
> protocol?
> Specifically, I'd like to known how you want to define the interval
> between two objects. Or is that for the sliced/indexed object to
> decide?
As I understand it:
The sliced object will only see integers. The PEP wants to give arbitrary
objects the possibility of pretending to be an integer that can be used
for indexing.
Georg
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