On 11/26/2017 3:35 AM, Eric V. Smith wrote:
On 11/26/2017 12:23 AM, Carl Meyer wrote:
A couple minor
questions:
If compare is True, then eq is ignored, and __eq__ and __ne__ will be
automatically generated.
IMO it's generally preferable to make nonsensical parameter combinations
an immediate error, rather than silently ignore one of them. Is there a
strong reason for letting nonsense pass silently here?
(I reviewed the previous thread; there was a lot of discussion about
enums/flags vs two boolean params, but I didn't see explicit discussion
of this issue; the only passing references I noticed said the invalid
combo should be "disallowed", e.g. Guido in [1], which to me implies "an
error.")
I think you're right here. I'll change it to a ValueError.
While creating an issue for this
(https://github.com/ericvsmith/dataclasses/issues/88), it occurs to me
that the class-level parameter really should be "order" or "orderable",
not "compare". It made more sense when it was called "cmp", but
"compare" now seems wrong.
Because "eq" says "can I compare two instances", and what's currently
called "compare" is "can I order two instances". Nick had a similar
suggestion before the PEP was written
(https://mail.python.org/pipermail/python-ideas/2017-May/045740.html).
The field-level parameter should stay "compare", because it's used for
both __gt__ and friends, as well as __eq__ and __ne__. It's saying "is
this field used in all of the comparison methods".
Eric.
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