Add Vector.zero as a class-level attribute

[nbraud]

No description provided.

[nbraud]

Looks like the version of dataclasses in PyPI, which we use with Py3.6, doesn't handle properly typing.ClassVar.

Edit: This is a known-issue: ericvsmith/dataclasses#143

[AstraLuma]

I guess comment out the annotation, with a link to that bug report.

[nbraud]

@astronouth7303 Without the annotation, dataclasses assumes it is an instance-level attribute and explodes.

I ported the fix from CPython to PyPI's dataclasses: ericvsmith/dataclasses#145

[nbraud]

Update: There already was a PR that backported that fix and another: ericvsmith/dataclasses#140
Unfortunately, it's been sitting there since December, so we can't expect upstream to merge that and cut a release any time soon. :(

[AstraLuma]

Ok, so what parts of dataclasses exactly chokes on this?

If we can't find a workaround, lets turn this into a factory method, or just leave it out altogether.

[nbraud]

Yeah, a factory method would work, but I'm willing to let this sit until there's a fixed version of dataclasses (or until we decide only to support Py3.7 and 3.8, whichever comes first) since it's really not high priority.

[nbraud]

bors try

[bors]

try

Timed out

[nbraud]

One macOS task seems to not have run. Rude :(

In any case, that confirms the testsuite passes now that #167 has been merged, though I would hold this up until either dataclasses is fixed or we drop Python 3.6 support.

[nbraud]

@AstraLuma Rebased to fix the merge conflict, should be finally good to go.

[AstraLuma]

This breaks on 3.6, right?

[nbraud]

This breaks on 3.6, right?

Not sure what you mean there, but:

• I merged Drop compatiblity with Python 3.6 #190 so 3.6 support is gone; presumably, if it was OK to go 2 years ago, it was still OK now.
• Even if we were to revert that, this code is fine on Py3.6; however, the unmaintained dataclasses compatibility shim for Py3.6 has (or had?) bugs that made it explode on ClassVar annotations, so for instance dataclasses.replace would choke on a Vector (IIRC throw an exception)

[AstraLuma]

bors r+

[bors]

Build succeeded:

• docs
• FreeBSD PYTHON:3.7
• FreeBSD PYTHON:3.8
• FreeBSD PYTHON:3.9
• lint
• Linux python:3.7-slim
• Linux python:3.8-slim
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• macOS PYTHON:3.8.6
• macOS PYTHON:3.9.0
• pep517
• Windows python:3.7-windowsservercore
• Windows python:3.8-windowsservercore
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