On 13 November 2016 at 04:07, Guido van Rossum <email@example.com> wrote:On Sat, Nov 12, 2016 at 5:46 PM, David Mertz <firstname.lastname@example.org> wrote:If we *do* want the name 'slice' as the spelling for the thing that can either be called or indexed to create a slice object, we could probably use some boilerplate like this:I can't stop you from doing that in your own session, but I don't want to reuse the builtin slice object for that. If this is so useful with Pandas maybe the Pandas library can define its own helper for this purpose.This reminds me @ vs .dot() for matrix multiplication a bit. Pandas has IndexSlicer, NumPy has index_exp, etc. I think it would be nice to have a simple common way to express this.
But here we have an additional ingredient -- generic types. I think that a reasonable compromise would be to simply continue the way proposed in http://bugs.python.org/
issue24379-- just add operator.subscript for this purpose. Pros:* subscript is not a class, so that subscript[...] will be not confused with generics;* this does not require patching built-ins;* all libraries that need this will get a "common interface" in stdlib, operator module seems to be good place for this.
The patch for operator.subscript was already applied, but it is now reverted because it caused a refleak.I have submitted a new patch that does not cause refleaks, I just replaced empty __slots__ with a __setattr__:it looks like __slots__ are not needed here to save memory (there is only a singleton instance),
they were used just to create an immutable object.