Why Python3

[Steven D'Aprano]

On Sun, 27 Jun 2010 20:12:10 -0400, Terry Reedy wrote:

> 7. Order comparisonS
> 
> In early Python1, I believe all objects could be (arbitrarily) compared
> and sorted. When Guido added the complex type, he decided not to add an
> arbitrary order, as he thought that could mask bugs.

I should point out that this wasn't a mere whimsy on Guido's part. 
Mathematically, supporting larger-than and less-than comparisons on 
complex numbers *is* a bug -- they're simply meaningless mathematically. 
(Which is greater, 2-1i or -1+2i?)

What Python needs[1] is a "sorting" operator, which is allowed to return 
a consistent if arbitrary sort order (perhaps lexicographic sort order?), 
separate from the ordinary > and < operators. This would allow the caller 
to sort lists of arbitrary items for display purposes, without implying 
anything about the relative size of items.



[1] For some definition of "need".


-- 
Steven