[Christopher Barker <python...@gmail.com>]
> ...
> But the biggest barrier is that it would be a fair bit of churn on the sort()
> functions
> (and the float class), and would only help for floats anyway. If someone want
> to propose this, please do -- but I don't think we should wait for that to do
> something
> with the statistics module. Also, if you want to pursue this, do go back and
> find
> the thread about type-checked sorting -- I think this is it:
>
> https://mail.python.org/pipermail/python-dev/2016-October/146613.html
>
> I'm not sure if anything ever came of that.
It was completed and is part of released CPython now.
But it's useless for this particular purpose. Leaving aside that
sort() is a wrong place to put this (as David M keeps saying, pass a
key= function to sort if you want a non-default sorting order),
type-checked sorting was purely a speed optimization, and applies only
to lists with a single type of element. So, e.g., it could plug in a
different sort order for lists containing only floats, but mix in a
single int (or any other non-float object) and the optimization is
100% disabled, leaving you with the default comparison logic instead.
That said, if we could wind back the clock, I'd make Python's floats
use something like the later IEEE total_order ordering instead. No
goofy results, nothing special about NaNs. For people who really
wanted IEEE's insane ;-) comparison semantics, that's fine - they'd
get it via, say, math.ieee_goofy_compare(a, b, flags) instead, where
flags is the bitwise-or of 0 or more of {LT, EQ, GT, UNORD}. E.g.,
pass GT | UNORD to return True iif the IEEE mandated result is
"greater than" or "unordered" (each IEEE comparison outcome is exactly
one of those four).
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