23.02.18 20:50, Chris Angelico пише:
Ignoring backward compatibility, it ought to be possible to (ab)use a
stride of zero for this. Calling slice.indices() on something with a
stride of zero raises ValueError, so there's no ambiguity. But it
would break code that iterates in a simple and obvious way, and (ugh
ugh) break it in a very nasty way: an infinite loop. I'm not happy
with that kind of breakage, even with multiple versions posting a
warning.
In the C API, there's PySlice_GetIndices "[y]ou probably do not want
to use this function" and PySlice_GetIndicesEx, the "[u]sable
replacement". Much as I dislike adding *yet another* function to do
basically the same job, I think that might be the less-bad way to do
this.
Actually PySlice_GetIndicesEx is deprecated too. It is not safe for
resizeable sequences since it is vulnerable to race condition. The pair
of PySlice_Unpack() and PySlice_AdjustIndices() replaces it in new code.
So now we have 4 functions for doing the same thing in C, 2 of them are
deprecated. Do you want to deprecate the other two and add new
replacements for them?
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