PEP: 314 Title: Metadata for Python Software Packages v1.1 Version: $Revision$ Last-Modified: $Date$ Author: A.M. Kuchling 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 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" 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: