python 3.7 binary wheels.

[fgregg]

This PR directs travis and appveyor to build binary wheels for python 3.7

[jamadden]

Adding a pyprojet.toml enables build isolation, meaning that packages installed in the virtualenv are ignored. Prior to pip 18.0, only binary wheels were allowed for build-system.requires. Taken together, this means that people installing BTrees from source (most likely those on platforms that don't already have binary wheels, e.g., BSD), must have the absolute latest pip.

I also wonder if it has any effect on those of us testing BTrees and persistent locally in the same virtualenv. Will we have to remember to pass --no-build-isolation to pip install -e .?

[mgedmin]

Which pip version introduced support for pyproject.toml? Surely older pips ignore it altogether, so there's only a brief range of versions where this could cause problems? (And wouldn't pip install'ing persistent beforehand create a wheel in pip's local cache that could then be reused?)

I think if people on weird platforms want to upgrade to the latest BTrees, they can also upgrade to the latest pip.

[jamadden]

Which pip version introduced support for pyproject.toml?

10.0b1 from March 31 of this year...a lot more recently than I thought.

Surely older pips ignore it altogether, so there's only a brief range of versions where this could cause problems?

Probably true, now that 18.0 is actually released.

And wouldn't pip install'ing persistent beforehand create a wheel in pip's local cache that could then be reused?

Hopefully?

I think if people on weird platforms want to upgrade to the latest BTrees, they can also upgrade to the latest pip.

I would think so too. I only mention it because every time I use a "new" setuptools feature in gevent, I get bug reports from people still using old versions (> 2 years). So I would suggest it's something that should explicitly be called out in the change notes.

[mgedmin]

Please also make .travis.yml to use 3.7 final instead of 3.7-dev.

(This may need an extra dist: xenial and sudo: true for that particular matrix.include job.)

[mgedmin]

Which pip version introduced support for pyproject.toml? Surely older pips ignore it altogether, so there's only a brief range of versions where this could cause problems? (And wouldn't pip install'ing persistent beforehand create a wheel in pip's local cache that could then be reused?)

I think if people on weird platforms want to upgrade to the latest BTrees, they can also upgrade to the latest pip.

[fgregg]

@mgedmin, travis-ci still does not natively support "3.7" so I don't think I should make the requested change.

[jamadden]

@fgregg It does, if you use 'dist: xenial' and 'sudo: true'. (See travis-ci/travis-ci#9069 or look at zope.proxy for an example.) Binary wheels built with a pre-release of 3.7 that old are pretty much useless, anyway, the ABI changed quite late in the release cycle.

[fgregg]

Thanks for the tip @jamadden and sorry that you had to repeat what @mgedmin said.

[fgregg]

@mgedmin @jamadden, would you be willing to make a release. Anything I can do to help with that?

[jamadden]

I've tagged and hopefully kicked off a release of 4.5.1. I left it with a minor version number bump as before because we previously claimed support with 3.7 (we just didn't distribute wheels). The pyproject.toml thing gave me a bit of pause, but it probably won't be a big deal (prepares salt and ketchup for hat).