[Distutils] PEP 566 - metadata 1.3 changes

[Dustin Ingram]

Hi all,

Thanks very much for all your suggestions and feedback.

I want to take a moment to summarize & respond to some outstanding issues from
this thread & previous threads. [0][1][2]

First, I'd like to reiterate that the goal of this PEP is to:

1. Define the Core Metadata document as the source for the specification;
2. Motivate, describe and formalize any new fields already in this spec;
3. Resolve any differences between this specification and other accepted PEPs.

With that in mind:

> How should multiple author-email and maintainer-email addresses be specified?

These fields already accept legal RFC-822 style headers, which includes the
possibility for multiple comma-separated addresses.

Note, however, that Warehouse currently incorrectly rejects such fields. [3]

> Should we add security-email and/or security-disclosure-instructions?

Let's defer this to a future version as it is not included in the current spec.

> Version specifiers and OR clauses

Let's defer this to a future version as it is not included in the current spec.

> Replacing hyphens with underscores when transforming to JSON-compatible metadata

This change was added to the draft.

> Differences with parentheses in version specifiers between PEP 345 and PEP 508

This change was added to the draft.

> AFAICT the only missing feature from old-Metadata-2.0 is "description as
> message body", which places readable description text after the key/value
> pairs.

Since twine does not currently support this for anything other than wheels, and
since it wouldn't be backwards-compatible, I'm inclined to defer this to a
future version.

> Metadata 1.3 vs Metadata 2.0

I agree with Nick here that since this version is backwards-compatible, that it
should remain Metadata 1.3.

In addition, I think we should avoid overloading the already-in-use "2.0"
version as possibly being either a "PEP 566 flavor 2.0" or a "PEP 426 flavor
2.0".

> Conclusion

I'm happy with this PEP as it stands, and I think it's ready to be formally
submitted for Daniel's review.

Thanks,
D.

[0]: https://mail.python.org/pipermail/distutils-sig/2017-December/031788.html
[1]: https://mail.python.org/pipermail/distutils-sig/2017-December/031805.html
[2]: https://mail.python.org/pipermail/distutils-sig/2017-December/031814.html
[3]: https://github.com/pypa/warehouse/issues/2679