Thanks Andrew for the excellent analysis quoted below. Further comments interleaved with yours.
On Fri, May 08, 2020 at 05:40:31PM -0700, Andrew Barnert via Python-ideas wrote: > If someone wants this proposal, it’s because they believe it’s _not_ a > misuse to use a tuple as a frozen list (or a list as a mutable tuple). > > If someone doesn’t want this proposal, the most likely reason > (although admittedly there are others) is because they believe it _is_ > a misuse to use a tuple as a frozen list. I don't think it is necessary to believe that it is *always* misuse, but only that it is *often* misuse and therefore `==` ought to take the conservative position and refuse to guess. I expect that nearly every Python programmer of sufficient experience has used a tuple as a de facto "frozen list" because it works and practicality beats purity. But that doesn't mean that I want my namedtuple PlayerStats(STR=10, DEX=12, INT=13, CON=9, WIS=8, CHR=12) to compare equal to my list [10, 12, 13, 9, 8, 12] by default. > It’s not always a misuse; it’s sometimes perfectly idiomatic to use a > tuple as an immutable hashable sequence. It doesn’t just happen to > 'work', it works, for principled reasons (tuple is a Sequence), and > this is a good thing.[1] > > It’s just that it’s _also_ common (probably a lot more common, but > even that isn’t necessary) to use it as an anonymous struct. > > So, the OP is right that (1,2,3)==[1,2,3] would sometimes be handy, > the opponents are right that it would often be misleading, and the > question isn’t which one is right, it’s just how often is often. And > the answer is obviously: often enough that it can’t be ignored. And > that’s all that matters here. Yes, I think there's a genuine need here. > And that’s why tuple is different from frozenset. Very few uses of > frozenset are as something other than a frozen set, so it’s almost > never misleading that frozensets equal sets; plenty of tuples aren’t > frozen lists, so it would often be misleading if tuples equaled lists. -- Steven _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/WXHODOZCS3HK2HOLZ2TQWAVYWBUWHDJV/ Code of Conduct: http://python.org/psf/codeofconduct/
