[Python-Dev] Edits to Metadata 1.2 to add extras (optional ependencies)

[Nick Coghlan]

On Fri, Aug 31, 2012 at 10:41 PM, R. David Murray <rdmurray at bitdance.com> wrote:
> It also allows for typo detection, which automatically interpreting
> prefix strings as extensions names would not.

+1 on retaining the explicit extension field, mainly for the
cross-validation benefits (including easily checking which extension
syntax is used by a module).

However, also +1 on using "/" as the extension separator to avoid
ambiguity in field names, as well as restoring the explicit
requirement that metadata entries use valid RFC 822 metasyntax. If the
precise rules can be articulated as a 3.3 email module policy, so much
the better.

I've now pushed Daniel's latest draft as PEP 426. I added the
following section on "Metadata Files", which restores some background
info on the overall file format that went AWOL in v1.2:

-----------------------------------------------------------------------
Metadata Files
==============

The syntax defined in this PEP is for use with Python distribution metadata
files. This file format is a single set of RFC-822 headers parseable by
the ``rfc822`` or ``email`` modules.  The field names listed in the
`Fields`_ section are used as the header names.

There are two standard locations for these metadata files:

* the ``PKG-INFO`` file included in the base directory of Python
  source distribution archives (as created by the distutils ``sdist``
  command)
* the ``dist-info/METADATA`` files in a Python installation database, as
  described in PEP 376.

Other tools involved in Python distribution may choose to record this
metadata in additional tool-specific locations (e.g. as part of a
binary distribution archive format).
-----------------------------------------------------------------------

As far as I know, the sdist archive format isn't actually defined
anywhere beyond "archives like those created by the distutils sdist
command".

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia