[Distutils] Current draft of PEP 314
Andrew Kuchling
akuchlin@mems-exchange.org
Wed May 14 13:30:03 2003
[Crossposted to Distutils-SIG and Catalog-SIG; followups set to
Distutils-SIG.]
Here's the current draft of PEP 314, which updates the format of the
PKG-INFO file originally specified in PEP 241. From the section
"Summary of Differences From PEP 241":
* Metadata-Version is now 1.1.
* Added the Classifiers field from PEP 301.
* Added fields: Download-URL, Requires, Provides, Obsoletes, Conflicts.
The remaining open issue is whether to deprecate the 'license' and
'platform' keyword arguments to setup(), on the grounds that
the 'classifiers' list contains entries for this, and there should be
only one way to do it.
Comments welcome.
--amk (www.amk.ca)
Dream? Give me your hand.
-- Death, in SANDMAN #69: "The Kindly Ones:13"
PEP: 314
Title: Metadata for Python Software Packages v1.1
Version: $Revision: 1.15 $
Last-Modified: $Date: 2003/05/14 17:12:55 $
Author: A.M. Kuchling <amk@amk.ca>
Status: Draft
Type: Standards Track
Content-type: text/plain
Created: 12-Apr-2003
Python-Version: 2.3
Post-History: 29-Apr-2003
Replaces: 241
Introduction
This PEP describes a mechanism for adding metadata to Python
packages. It includes specifics of the field names, and their
semantics and usage.
This document specifies version 1.1 of the metadata format.
Version 1.0 is specified in PEP 241.
Including Metadata in Packages
The Distutils 'sdist' command will extract the metadata fields
from the arguments and write them to a file in the generated
zipfile or tarball. This file will be named PKG-INFO and will be
placed in the top directory of the source distribution (where the
README, INSTALL, and other files usually go).
Developers may not provide their own PKG-INFO file. The "sdist"
command will, if it detects an existing PKG-INFO file, terminate
with an appropriate error message. This should prevent confusion
caused by the PKG-INFO and setup.py files being out of sync.
The PKG-INFO file format is a single set of RFC-822 headers
parseable by the rfc822.py module. The field names listed in the
following section are used as the header names.
Fields
This section specifies the names and semantics of each of the
supported metadata fields.
Fields marked with "(Multiple use)" may be specified multiple
times in a single PKG-INFO file. Other fields may only occur
once in a PKG-INFO file. Fields marked with "(optional)" are
not required to appear in a valid PKG-INFO file; all other
fields must be present.
Metadata-Version
Version of the file format; currently "1.0" and "1.1" are the
only legal values here.
Example:
Metadata-Version: 1.1
Name
The name of the package.
Example:
Name: BeagleVote
Version
A string containing the package's version number. This
field should be parseable by one of the Version classes
(StrictVersion or LooseVersion) in the distutils.version
module.
Example:
Version: 1.0a2
Platform (multiple use)
A comma-separated list of platform specifications, summarizing
the operating systems supported by the package. The major
supported platforms are listed below, but this list is
necessarily incomplete.
POSIX, MacOS, Windows, BeOS, PalmOS.
Example:
Platform: POSIX, Windows
Supported-Platform (multiple use)
Binary distributions containing a PKG-INFO file will use the
Supported-Platform field in their metadata to specify the OS and
CPU for which the binary package was compiled. The semantics of
the Supported-Platform field are not specified in this PEP.
Example:
Supported-Platform: RedHat 7.2
Supported-Platform: i386-win32-2791
Summary
A one-line summary of what the package does.
Example:
Summary: A module for collecting votes from beagles.
Description (optional)
A longer description of the package that can run to several
paragraphs. Software that deals with metadata should not assume
any maximum size for this field, though people shouldn't include
their instruction manual as the description.
The contents of this field can be written using reStructuredText
markup [1]. For programs that work with the metadata,
supporting markup is optional; programs can also display the
contents of the field as-is. This means that authors should be
conservative in the markup they use.
Example:
Description: This module collects votes from beagles
in order to determine their electoral wishes.
Do *not* try to use this module with basset hounds;
it makes them grumpy.
Keywords (optional)
A list of additional keywords to be used to assist searching
for the package in a larger catalog.
Example:
Keywords: dog puppy voting election
Home-page (optional)
A string containing the URL for the package's home page.
Example:
Home-page: http://www.example.com/~cschultz/bvote/
Download-URL
A string containing the URL from which this version of the package
can be downloaded. (This means that the URL can't be something like
".../package-latest.tgz", but instead must be "../package-0.45.tgz".)
Author (optional)
A string containing the author's name at a minimum; additional
contact information may be provided.
Example:
Author: C. Schultz, Universal Features Syndicate,
Los Angeles, CA <cschultz@peanuts.example.com>
Author-email
A string containing the author's e-mail address. It can contain
a name and e-mail address in the legal forms for a RFC-822
'From:' header. It's not optional because cataloging systems
can use the e-mail portion of this field as a unique key
representing the author. A catalog might provide authors the
ability to store their GPG key, personal home page, and other
additional metadata *about the author*, and optionally the
ability to associate several e-mail addresses with the same
person. Author-related metadata fields are not covered by this
PEP.
Example:
Author-email: "C. Schultz" <cschultz@example.com>
License
A string selected from a short list of choices, specifying the
license covering the package. Some licenses result in the
software being freely redistributable, so packagers and
resellers can automatically know that they're free to
redistribute the software. Other licenses will require
a careful reading by a human to determine how the software can be
repackaged and resold.
The choices are:
Artistic, BSD, DFSG, GNU GPL, GNU LGPL, "MIT",
Mozilla PL, "public domain", Python, Qt PL, Zope PL, unknown,
nocommercial, nosell, nosource, shareware, other
Definitions of some of the licenses are:
DFSG The license conforms to the Debian Free Software
Guidelines, but does not use one of the other
DFSG conforming licenses listed here.
More information is available at:
http://www.debian.org/social_contract#guidelines
Python Python 1.6 or higher license. Version 1.5.2 and
earlier are under the MIT license.
public domain Software is public domain, not copyrighted.
unknown Status is not known
nocommercial Free private use but commercial use not permitted
nosell Free use but distribution for profit by arrangement
nosource Freely distributable but no source code
shareware Payment is requested if software is used
other General category for other non-DFSG licenses
Some of these licenses can be interpreted to mean the software is
freely redistributable. The list of redistributable licenses is:
Artistic, BSD, DFSG, GNU GPL, GNU LGPL, "MIT",
Mozilla PL, "public domain", Python, Qt PL, Zope PL,
nosource, shareware
Note that being redistributable does not mean a package
qualifies as free software, 'nosource' and 'shareware' being
examples.
Example:
License: MIT
Classifier (multiple use)
Each entry is a string giving a single classification value
for the package. Classifiers are described in PEP 301 [2].
Examples:
Classifier: Development Status :: 4 - Beta
Classifier: Environment :: Console (Text Based)
Requires (multiple use)
Each entry contains a string describing some other component or
module required by this package.
The format of a requirement string is simple: an arbitrary
sequence of characters, optionally followed by a version
declaration within parentheses. Leading and trailing whitespace
are ignored, and whitespace within the string is normalized to a
single space.
A version declaration is a series of conditional operators and
version numbers, separated by commas. Conditional operators
must be one of "<", ">", "<=", ">=", "==", and "!=". Version
numbers must be in the format accepted by the
distutils.version.StrictVersion class: two or three
dot-separated numeric components, with an optional "pre-release"
tag on the end consisting of the letter 'a' or 'b' followed by a
number. Example version numbers are "1.0", "2.3a2", "1.3.99",
Any number of conditional operators can be specified, e.g.
the string ">1.0, !=1.3.4, <2.0" is a legal version declaration.
All of the following are possible requirement strings: "rfc822",
"zlib (>=1.1.4)", "XML parser".
There's no canonical list of what strings should be used; the
Python community is left to choose its own standards.
Example:
Requires: re
Requires: sys
Requires: zlib
Requires: pyexpat (>1.0)
Requires: DB-API 2.0 module
Provides (multiple use)
Each entry contains a string describing a component or
module that will be provided by this package once it is
installed. These strings should match the ones used in
Requirements fields. Version declarations cannot be supplied;
instead the package's version number will be used.
Example:
Provides: xml
Provides: xml.utils
Provides: xml.utils.iso8601
Provides: xml.dom
Obsoletes (multiple use)
Each entry contains a string describing a component or module
that this package renders obsolete, meaning that the two packages
should not be installed at the same time. Version declarations
can be supplied.
The most common use of this field will be in case a package name
changes, e.g. Gorgon 2.3 gets subsumed into Torqued Python 1.0.
When you install Torqued Python, the Gorgon package should be
removed.
Example:
Obsoletes: Gorgon
Conflicts (multiple use)
Each entry contains a string describing a component or module
that conflicts with this package, meaning that the two packages
should not be installed at the same time. Version declarations
can be supplied.
Conflict resolution probably isn't very important for Python
programs, because few extensions will cause problems for other
extensions, unless they happen to be using the same package
name. This field name is being defined here for future use.
Conflicts: Gorgon
Summary of Differences From PEP 241
* Metadata-Version is now 1.1.
* Added the Classifiers field from PEP 301.
* Added fields: Download-URL, Requires, Provides, Obsoletes, Conflicts.
Open issues
With the addition of the 'Classifiers' field, should the Platform
and License fields be removed?
Acknowledgements
Richard Jones suggested using reST for the Description field.
References
[1] reStructuredText
http://docutils.sourceforge.net/
[2] PEP 301
http://www.python.org/peps/pep-0301.html
Copyright
This document has been placed in the public domain.
Local Variables:
mode: indented-text
indent-tabs-mode: nil
End: