On Sep 10, 2017, at 20:08, Nathaniel Smith <[email protected]> wrote: > > I've sometimes wished that attrs let me control whether it generated equality > methods (eq/ne/hash) separately from ordering methods (lt/gt/...). Maybe the > cmp= argument should take an enum with options none/equality-only/full?
I have had use cases where I needed equality comparisons but not ordered comparisons, so I’m in favor of the option to split them. (atm, I can’t bring up a specific case, but it’s not uncommon.) Given that you only want to support the three states that Nathaniel describes, I think an enum makes the most sense, and it certainly would read well. I.e. there’s no sense in supporting the ordered comparisons and not equality, so that’s not a state that needs to be represented. I’d make one other suggestion here: please let’s not call the keyword `cmp`. That’s reminiscent of Python 2’s `cmp` built-in, which of course doesn’t exist in Python 3. Using `cmp` is just an unnecessarily obfuscating abbreviation. I’d suggest just `compare` with an enum like so: enum Compare(enum.Enum): none = 1 unordered = 2 ordered = 3 One thing I can’t avoid is DRY: from dataclasses import Compare, dataclass @dataclass(compare=Compare.unordered) class Foo: # ... Maybe exposing the enum items in the module namespace? ——dataclasses/__init__.py----- from enum import Enum class Compare(Enum): none = 1 unordered = 2 ordered =3 none = Compare.none unordered = Compare.unordered ordered = Compare.ordered ——dataclasses/__init__.py----- from dataclasses import dataclass, unordered @dataclass(compare=unordered) class Foo: # ... Cheers, -Barry
Attachment:
signature.asc
Description: Message signed with OpenPGP
_______________________________________________ Python-Dev mailing list [email protected] https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com