[Python-Dev] PEP 557: Data Classes (original) (raw)

Steven D'Aprano steve at pearwood.info
Fri Sep 8 14:38:06 EDT 2017

On Fri, Sep 08, 2017 at 10:37:12AM -0700, Nick Coghlan wrote:

> def eq(self, other): > if other.class is self.class: > return (self.name, self.unitprice, self.quantityonhand) == > (other.name, other.unitprice, other.quantityonhand) > return NotImplemented

My one technical question about the PEP relates to the use of an exact type check in the comparison methods, rather than "isinstance(other, self.class)".

I haven't read the whole PEP in close detail, but that method stood out for me too. Only, unlike Nick, I don't think I agree with the decision.

I'm also not convinced that we should be adding ordered comparisons (lt gt etc) by default, if these DataClasses are considered more like structs/records than tuples. The closest existing equivalent to a struct in the std lib (apart from namedtuple) is, I think, SimpleNamespace, and they are unorderable.

-- Steve

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