Re: [Python-Dev] Concerns about method overriding and subclassing with dataclasses

2018年1月05日 05:11:20 -0800

On 1/2/2018 12:01 AM, Guido van Rossum wrote:
On Mon, Jan 1, 2018 at 8:50 PM, Ethan Smith <[email protected] <mailto:[email protected]>> wrote:
 On Mon, Jan 1, 2018 at 5:03 PM, Chris Barker <[email protected]
 <mailto:[email protected]>> wrote:
 On Sat, Dec 30, 2017 at 7:27 AM, Stephen J. Turnbull
 <[email protected]
 <mailto:[email protected]>> wrote:
  Just use the simple rule that a new
 __repr__ is generated unless provided in the dataclass.
 are we only talking about __repr__ here ???
 I interpreted Guido's proposal as being about all methods -- we
 _may_ want something special for __repr__, but I hope not.
 [...]
 I interpreted this to be for all methods as well, which makes sense.
 Special casing just __repr__ doesn't make sense to me, but I will
 wait for Guido to clarify.
Indeed, I just wrote __repr__ for simplicity. This should apply to all special methods. (Though there may be some complications for __eq__/__ne__ and for the ordering operators.) On Mon, Jan 1, 2018 at 9:44 PM, Chris Barker <[email protected] <mailto:[email protected]>> wrote:
 On Mon, Jan 1, 2018 at 7:50 PM, Ethan Smith <[email protected]
 <mailto:[email protected]>> wrote:
 Will you get the "right" __repr__ now if you derive a
 dataclass from a dataclass? That would be a nice feature.
 The __repr__ will be generated by the child dataclass unless the
 user overrides it. So I believe this is the "right" __repr__.
 what I was wondering is if the child will know about all the fields
 in the parent -- so it could make a full __repr__.
Yes, there's a class variable (__dataclass_fields__) that identifies the parent fields. The PEP doesn't mention this or the fact that special methods (like __repr__ and __init__) can tell whether a base class is a dataclass. It probably should though. (@Eric)
I think that's covered in this section: https://www.python.org/dev/peps/pep-0557/#inheritance
Eric.
_______________________________________________
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

Reply via email to