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

Eric V. Smith eric at trueblade.com
Mon Nov 27 05:56:29 EST 2017

On 11/27/2017 1:04 AM, Nick Coghlan wrote:

On 27 November 2017 at 15:04, Greg Ewing <greg.ewing at canterbury.ac.nz> wrote:

Nick Coghlan wrote:

Perhaps the check could be: (type(lhs) == type(rhs) or fields(lhs) == fields(rhs)) and all (individual fields match) I think the types should always have to match, or at least one should be a subclass of the other. Consider: @dataclass class Point3d: x: float y: float z: float @dataclass class Vector3d: x: float y: float z: float Points and vectors are different things, and they should never compare equal, even if they have the same field names and values. And I guess if folks actually want more permissive structure-based matching, that's one of the features that collections.namedtuple offers that data classes don't.

And in this case you could also do: astuple(point) == astuple(vector)

Eric.

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