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= PEP 1 : PEP Purpose and Guidelines = [[PageOutline]] || '''PEP''' || 1 || || '''Title''' || ''PEP'' Purpose and Guidelines || || '''Version''' || [http://hg.python.org/peps/file/f3358939e05e/pep-0001.txt f3358939e05e] || || '''Last-Modified''' || [http://hg.python.org/peps/file/tip/pep-0001.txt 2012-05-18 10:08:09 -0400 (Fri, 18 May 2012)] || || '''Author''' || Barry Warsaw, Jeremy Hylton, David Goodger, Nick Coghlan || || '''Status''' || Active || || '''Type''' || Process || || '''Content-Type''' || [http://www.python.org/dev/peps/pep-0012 text/x-rst] || || '''Created''' || 13-Jun-2000 || || '''Post-History''' || 21-Mar-2001, 29-Jul-2002, 03-May-2003, 05-May-2012 || ---- == What is a PEP? #what-is-a-pep '''PEP''' stands for ''Python Enhancement Proposal''. A ''PEP'' is a design document providing information to the ''Python'' community, or describing a new feature for ''Python'' or its processes or environment. The ''PEP'' should provide a concise technical specification of the feature and a rationale for the feature. We intend PEPs to be the primary mechanisms for proposing major new features, for collecting community input on an issue, and for documenting the design decisions that have gone into ''Python''. The ''PEP'' author is responsible for building consensus within the community and documenting dissenting opinions. Because the PEPs are maintained as text files in a versioned repository, their revision history is the historical record of the feature proposal ^[#id8 1]^ . == PEP Types #pep-types There are three kinds of PEP: - A '''Standards Track PEP''' describes a new feature or implementation for ''Python''. - An '''Informational PEP''' describes a ''Python'' design issue, or provides general guidelines or information to the ''Python'' community, but does not propose a new feature. ''Informational'' PEPs do not necessarily represent a ''Python'' community consensus or recommendation, so users and implementers are free to ignore Informational PEPs or follow their advice. - A '''Process PEP''' describes a process surrounding ''Python'', or proposes a change to (or an event in) a process. ''Process'' PEPs are like ''Standards Track'' PEPs but apply to areas other than the ''Python'' language itself. They may propose an implementation, but not to Python's codebase; they often require community consensus; unlike Informational PEPs, they are more than recommendations, and users are typically not free to ignore them. Examples include procedures, guidelines, changes to the decision-making process, and changes to the tools or environment used in ''Python'' development. Any meta-PEP is also considered a ''Process'' PEP. == PEP Work Flow #pep-work-flow === Python's BDFL #python-s-bdfl There are several reference in this ''PEP'' to the '''BDFL'''. This acronym stands for ''Benevolent Dictator for Life'' and refers to ''Guido van Rossum'', the original creator of, and the final design authority for, the ''Python'' programming language. === Submitting a PEP #submitting-a-pep The ''PEP'' editors assign ''PEP'' numbers and change their status. Please send all PEP-related email to <[email protected]> (no cross-posting please). Also see [#pep-editor-responsibilities-workflow PEP Editor Responsibilities & Workflow] below. The ''PEP'' process begins with a new idea for Python. It is highly recommended that a single ''PEP'' contain a single key proposal or new idea. Small enhancements or patches often don't need a ''PEP'' and can be injected into the ''Python'' development work flow with a patch submission to the ''Python'' [http://bugs.python.org/ issue tracker] . The more focused the PEP, the more successful it tends to be. The ''PEP'' editor reserves the right to reject ''PEP'' proposals if they appear too unfocused or too broad. If in doubt, split your ''PEP'' into several well-focused ones. Each ''PEP'' must have a champion -- someone who writes the ''PEP'' using the style and format described below, shepherds the discussions in the appropriate forums, and attempts to build community consensus around the idea. The ''PEP'' champion (a.k.a. Author) should first attempt to ascertain whether the idea is PEP-able. Posting to the comp.lang.python newsgroup (a.k.a. [email protected] mailing list) or the python-ideas mailing list is the best way to go about this. Vetting an idea publicly before going as far as writing a ''PEP'' is meant to save the potential author time. Many ideas have been brought forward for changing ''Python'' that have been rejected for various reasons. Asking the ''Python'' community first if an idea is original helps prevent too much time being spent on something that is guaranteed to be rejected based on prior discussions (searching the internet does not always do the trick). It also helps to make sure the idea is applicable to the entire community and not just the author. Just because an idea sounds good to the author does not mean it will work for most people in most areas where ''Python'' is used. Once the champion has asked the ''Python'' community as to whether an idea has any chance of acceptance, a draft ''PEP'' should be presented to python-ideas. This gives the author a chance to flesh out the draft ''PEP'' to make properly formatted, of high quality, and to address initial concerns about the proposal. Following a discussion on python-ideas, the proposal should be sent to the python-dev list with the draft ''PEP'' and the ''PEP'' editors <[email protected]>. This draft must be written in ''PEP'' style as described below, else it will be sent back without further regard until proper formatting rules are followed. If the ''PEP'' editor approves, they will assign the ''PEP'' a number, label it as Standards Track, Informational, or Process, give it status "Draft", and create and check-in the initial draft of the PEP. The ''PEP'' editor will not unreasonably deny a PEP. Reasons for denying ''PEP'' status include duplication of effort, being technically unsound, not providing proper motivation or addressing backwards compatibility, or not in keeping with the ''Python'' philosophy. The BDFL can be consulted during the approval phase, and is the final arbiter of the draft's PEP-ability. Developers with hg push privileges for the [http://hg.python.org/peps PEP repository] may claim ''PEP'' numbers directly by creating and committing a new PEP. When doing so, the developer must handle the tasks that would normally be taken care of by the ''PEP'' editors (see [#pep-editor-responsibilities-workflow PEP Editor Responsibilities & Workflow]). This includes ensuring the initial version meets the expected standards for submitting a PEP. Alternately, even developers may choose to submit PEPs through the ''PEP'' editors. When doing so, let the ''PEP'' editors know you have hg push privileges and they can guide you through the process of updating the ''PEP'' repository directly. As updates are necessary, the ''PEP'' author can check in new versions if they have hg push privileges, or can email new ''PEP'' versions to the ''PEP'' editors for publication. Standards Track PEPs consist of two parts, a design document and a reference implementation. The ''PEP'' should be reviewed and accepted before a reference implementation is begun, unless a reference implementation will aid people in studying the PEP. Standards Track PEPs must include an implementation -- in the form of code, a patch, or a URL to same -- before it can be considered Final. PEP authors are responsible for collecting community feedback on a ''PEP'' before submitting it for review. However, wherever possible, long open-ended discussions on public mailing lists should be avoided. Strategies to keep the discussions efficient include: setting up a separate SIG mailing list for the topic, having the ''PEP'' author accept private comments in the early design phases, setting up a wiki page, etc. ''PEP'' authors should use their discretion here. === PEP Review & Resolution #pep-review-resolution Once the authors have completed a PEP, they may request a review for style and consistency from the ''PEP'' editors. However, the content and final acceptance of the ''PEP'' must be requested of the BDFL, usually via an email to the python-dev mailing list. PEPs are reviewed by the BDFL and his chosen consultants, who may accept or reject a ''PEP'' or send it back to the author(s) for revision. For a ''PEP'' that is predetermined to be acceptable (e.g., it is an obvious win as-is and/or its implementation has already been checked in) the BDFL may also initiate a ''PEP'' review, first notifying the ''PEP'' author(s) and giving them a chance to make revisions. The final authority for ''PEP'' approval is the BDFL. However, whenever a new ''PEP'' is put forward, any core developer that believes they are suitably experienced to make the final decision on that ''PEP'' may offer to serve as the BDFL's delegate (or "PEP czar") for that PEP. If their self-nomination is accepted by the other core developers and the BDFL, then they will have the authority to approve (or reject) that PEP. This process happens most frequently with PEPs where the BDFL has granted in principle approval for something to be done, but there are details that need to be worked out before the ''PEP'' can be accepted. If the final decision on a ''PEP'' is to be made by a delegate rather than directly by the BDFL, this will be recorded by including the "BDFL-Delegate" header in the PEP. For a ''PEP'' to be accepted it must meet certain minimum criteria. It must be a clear and complete description of the proposed enhancement. The enhancement must represent a net improvement. The proposed implementation, if applicable, must be solid and must not complicate the interpreter unduly. Finally, a proposed enhancement must be "pythonic" in order to be accepted by the BDFL. (However, "pythonic" is an imprecise term; it may be defined as whatever is acceptable to the BDFL. This logic is intentionally circular.) See [http://www.python.org/dev/peps/pep-0002 PEP 2] for standard library module acceptance criteria. Once a ''PEP'' has been accepted, the reference implementation must be completed. When the reference implementation is complete and incorporated into the main source code repository, the status will be changed to "Final". A ''PEP'' can also be assigned status "Deferred". The ''PEP'' author or editor can assign the ''PEP'' this status when no progress is being made on the PEP. Once a ''PEP'' is deferred, the ''PEP'' editor can re-assign it to draft status. A ''PEP'' can also be "Rejected". Perhaps after all is said and done it was not a good idea. It is still important to have a record of this fact. The "Withdrawn" status is similar - it means that the ''PEP'' author themselves has decided that the ''PEP'' is actually a bad idea, or has accepted that a competing proposal is a better alternative. When a ''PEP'' is Accepted, Rejected or Withdrawn, the ''PEP'' should be updated accordingly. In addition to updating the status field, at the very least the Resolution header should be added with a link to the relevant post in the python-dev mailing list archives. PEPs can also be superseded by a different PEP, rendering the original obsolete. This is intended for Informational PEPs, where version 2 of an API can replace version 1. The possible paths of the status of PEPs are as follows: [[Image(http://www.python.org/dev/peps/pep-0001/pep-0001-1.png, alt=PEP lifecycle, title=PEP lifecycle, link=http://www.python.org/dev/peps/pep-0001/#id30)]] Some Informational and Process PEPs may also have a status of "Active" if they are never meant to be completed. E.g. ''PEP'' 1 (this PEP). === PEP Maintenance #pep-maintenance In general, Standards track PEPs are no longer modified after they have reached the Final state. Once a ''PEP'' has been completed, the Language and Standard Library References become the formal documentation of the expected behavior. Informational and Process PEPs may be updated over time to reflect changes to development practices and other details. The precise process followed in these cases will depend on the nature and purpose of the ''PEP'' being updated. == What belongs in a successful PEP? #what-belongs-in-a-successful-pep Each ''PEP'' should have the following parts: 1. '''Preamble''' -- [http://www.faqs.org/rfcs/rfc822.html RFC 822] style headers containing meta-data about the PEP, including the ''PEP'' number, a short descriptive title (limited to a maximum of 44 characters), the names, and optionally the contact info for each author, etc. 2. '''Abstract''' -- a short (~200 word) description of the technical issue being addressed. 3. '''Copyright/public domain''' -- Each ''PEP'' must either be explicitly labeled as placed in the public domain (see this ''PEP'' as an example) or licensed under the [http://www.opencontent.org/openpub/ Open Publication License]. 4. '''Specification''' -- The technical specification should describe the syntax and semantics of any new language feature. The specification should be detailed enough to allow competing, interoperable implementations for any of the current ''Python'' platforms (CPython, Jython, ''Python'' .NET). 5. '''Motivation''' -- The motivation is critical for PEPs that want to change the ''Python'' language. It should clearly explain why the existing language specification is inadequate to address the problem that the ''PEP'' solves. ''PEP'' submissions without sufficient motivation may be rejected outright. 6. '''Rationale''' -- The rationale fleshes out the specification by describing what motivated the design and why particular design decisions were made. It should describe alternate designs that were considered and related work, e.g. how the feature is supported in other languages. The rationale should provide evidence of consensus within the community and discuss important objections or concerns raised during discussion. 7. '''Backwards Compatibility''' -- All PEPs that introduce backwards incompatibilities must include a section describing these incompatibilities and their severity. The ''PEP'' must explain how the author proposes to deal with these incompatibilities. ''PEP'' submissions without a sufficient backwards compatibility treatise may be rejected outright. 8. '''Reference Implementation''' -- The reference implementation must be completed before any ''PEP'' is given status "Final", but it need not be completed before the ''PEP'' is accepted. It is better to finish the specification and rationale first and reach consensus on it before writing code. The final implementation must include test code and documentation appropriate for either the ''Python'' language reference or the standard library reference. == PEP Formats and Templates #pep-formats-and-templates There are two ''PEP'' formats available to authors: plaintext and [http://docutils.sourceforge.net/rst.html reStructuredText]. Both are UTF-8-encoded text files. Plaintext PEPs are written with minimal structural markup that adheres to a rigid style. [http://www.python.org/dev/peps/pep-0009 PEP 9] contains a instructions and a template you can use to get started writing your plaintext PEP. [http://docutils.sourceforge.net/rst.html ReStructuredText] PEPs allow for rich markup that is still quite easy to read, but results in much better-looking and more functional HTML. ''PEP'' 12 contains instructions and a template for reStructuredText PEPs. There is a ''Python'' script that converts both styles of PEPs to HTML for viewing on the web [#id12 5]. Parsing and conversion of plaintext PEPs is self-contained within the script. reStructuredText PEPs are parsed and converted by [http://docutils.sourceforge.net/ Docutils] code called from the script. == PEP Header Preamble #pep-header-preamble Each ''PEP'' must begin with an [http://www.faqs.org/rfcs/rfc822.html RFC 822] style header preamble. The headers must appear in the following order. Headers marked with "*" are optional and are described below. All other headers are required. {{{ PEP: <pep number> Title: <pep title> Version: <version string> Last-Modified: <date string> Author: <list of authors' real names and optionally, email addrs> * BDFL-Delegate: <PEP czar's real name> * Discussions-To: <email address> Status: <Draft | Active | Accepted | Deferred | Rejected | Withdrawn | Final | Superseded> Type: <Standards Track | Informational | Process> * Content-Type: <text/plain | text/x-rst> * Requires: <pep numbers> Created: <date created on, in dd-mmm-yyyy format> * Python-Version: <version number> Post-History: <dates of postings to python-list and python-dev> * Replaces: <pep number> * Superseded-By: <pep number> * Resolution: <url> }}} The Author header lists the names, and optionally the email addresses of all the authors/owners of the PEP. The format of the Author header value must be Random J. User <[email protected]> if the email address is included, and just Random J. User if the address is not given. For historical reasons the format ''[email protected] (Random J. User)'' may appear in a PEP, however new PEPs must use the mandated format above, and it is acceptable to change to this format when PEPs are updated. If there are multiple authors, each should be on a separate line following [http://www.faqs.org/rfcs/rfc2822.html RFC 2822] continuation line conventions. Note that personal email addresses in PEPs will be obscured as a defense against spam harvesters. The BDFL-Delegate field is used to record cases where the final decision to approve or reject a ''PEP'' rests with someone other than the BDFL. (The delegate's email address is currently omitted due to a limitation in the email address masking for reStructuredText PEPs) Note: The Resolution header is required for Standards Track PEPs only. It contains a URL that should point to an email message or other web resource where the pronouncement about the ''PEP'' is made. While a ''PEP'' is in private discussions (usually during the initial Draft phase), a Discussions-To header will indicate the mailing list or URL where the ''PEP'' is being discussed. No Discussions-To header is necessary if the ''PEP'' is being discussed privately with the author, or on the python-list, python-ideas or python-dev email mailing lists. Note that email addresses in the Discussions-To header will not be obscured. The Type header specifies the type of PEP: '''Standards Track''', '''Informational''', or '''Process'''. The format of a ''PEP'' is specified with a '''Content-Type''' header. The acceptable values are "text/plain" for plaintext PEPs (see [http://www.python.org/dev/peps/pep-0009 PEP]) and "text/x-rst" for reStructuredText PEPs (see [http://www.python.org/dev/peps/pep-0012 PEP 12]). Plaintext ("text/plain") is the default if no ''Content-Type'' header is present. The Created header records the date that the ''PEP'' was assigned a number, while Post-History is used to record the dates of when new versions of the ''PEP'' are posted to python-list and/or python-dev. Both headers should be in dd-mmm-yyyy format, e.g. 14-Aug-2001. Standards Track PEPs must have a Python-Version header which indicates the version of ''Python'' that the feature will be released with. Informational and Process PEPs do not need a Python-Version header. PEPs may have a Requires header, indicating the ''PEP'' numbers that this ''PEP'' depends on. PEPs may also have a Superseded-By header indicating that a ''PEP'' has been rendered obsolete by a later document; the value is the number of the ''PEP'' that replaces the current document. The newer ''PEP'' must have a Replaces header containing the number of the ''PEP'' that it rendered obsolete. == Auxiliary Files #auxiliary-files PEPs may include auxiliary files such as diagrams. Such files must be named pep-XXXX-Y.ext, where "XXXX" is the ''PEP'' number, "Y" is a serial number (starting at 1), and "ext" is replaced by the actual file extension (e.g. "png"). == Reporting ''PEP'' Bugs, or Submitting ''PEP'' Updates #reporting-pep-bugs-or-submitting-pep-updates How you report a bug, or submit a ''PEP'' update depends on several factors, such as the maturity of the PEP, the preferences of the ''PEP'' author, and the nature of your comments. For the early draft stages of the PEP, it's probably best to send your comments and changes directly to the ''PEP'' author. For more mature, or finished PEPs you may want to submit corrections to the ''Python'' [http://bugs.python.org/ issue tracker] so that your changes don't get lost. If the ''PEP'' author is a ''Python'' developer, assign the bug/patch to him, otherwise assign it to the ''PEP'' editor. When in doubt about where to send your changes, please check first with the ''PEP'' author and/or ''PEP'' editor. PEP authors who are also ''Python'' committers can update the PEPs themselves by using "hg push" to submit their changes. == Transferring ''PEP'' Ownership #transferring-pep-ownership It occasionally becomes necessary to transfer ownership of PEPs to a new champion. In general, we'd like to retain the original author as a co-author of the transferred PEP, but that's really up to the original author. A good reason to transfer ownership is because the original author no longer has the time or interest in updating it or following through with the ''PEP'' process, or has fallen off the face of the 'net (i.e. is unreachable or not responding to email). A bad reason to transfer ownership is because you don't agree with the direction of the PEP. We try to build consensus around a PEP, but if that's not possible, you can always submit a competing PEP. If you are interested in assuming ownership of a PEP, send a message asking to take over, addressed to both the original author and the ''PEP'' editor <[email protected]>. If the original author doesn't respond to email in a timely manner, the ''PEP'' editor will make a unilateral decision (it's not like such decisions can't be reversed :). == PEP Editor Responsibilities & Workflow #pep-editor-responsibilities-workflow A ''PEP'' editor must subscribe to the <[email protected]> list. All PEP-related correspondence should be sent (or CC'd) to <[email protected]> (but please do not cross-post!). For each new ''PEP'' that comes in an editor does the following: - Read the ''PEP'' to check if it is ready: sound and complete. The ideas must make technical sense, even if they don't seem likely to be accepted. - The title should accurately describe the content. - Edit the ''PEP'' for language (spelling, grammar, sentence structure, etc.), markup (for reST PEPs), code style (examples should match [http://www.python.org/dev/peps/pep-0008 PEP 8] & 7). If the ''PEP'' isn't ready, the editor will send it back to the author for revision, with specific instructions. Once the ''PEP'' is ready for the repository, the ''PEP'' editor will: - Assign a ''PEP'' number (almost always just the next available number, but sometimes it's a special/joke number, like 666 or 3141). (Clarification: For ''Python'' 3, we used numbers in the 3000s for Py3k-specific proposals. But now that all new features go into ''Python'' 3 only, we're back to using numbers in the 100s again. Remember that numbers below 100 are meta-PEPs.) - Add the ''PEP'' to a local clone of the ''PEP'' repository. For mercurial work flow instructions, follow [http://docs.python.org/devguide The Python Developers Guide] The mercurial repo for the peps is: {{{ http://hg.python.org/peps/ }}} - Run ./genpepindex.py and ./pep2html.py <PEP Number> to ensure they are generated without errors. If either triggers errors, then the web site will not be updated to reflect the ''PEP'' changes. - Commit and push the new (or updated) PEP - Monitor python.org to make sure the ''PEP'' gets added to the site properly. - Send email back to the ''PEP'' author with next steps (post to python-list & -dev). Updates to existing PEPs also come in to [email protected]. Many ''PEP'' authors are not ''Python'' committers yet, so ''PEP'' editors do the commits for them. Many PEPs are written and maintained by developers with write access to the ''Python'' codebase. The ''PEP'' editors monitor the python-checkins list for ''PEP'' changes, and correct any structure, grammar, spelling, or markup mistakes we see. The editors don't pass judgment on PEPs. We merely do the administrative & editorial part. Except for times like this, there's relatively low volume. == Resources #resources - [http://www.python.org/dev/peps/ Index of Python Enhancement Proposals] - [http://docs.python.org/devguide/communication.html Following Python's Development] - [http://docs.python.org/devguide/ Python Developer's Guide] - [http://docs.python.org/devguide/faq.html Frequently Asked Questions for Developers] == References and Footnotes #references-and-footnotes {{{#!span id="id8" }}} 1. This historical record is available by the normal hg commands for retrieving older revisions, and can also be browsed via HTTP here: http://hg.python.org/peps/ 2. PEP 2, Procedure for Adding New Modules, Faassen (http://www.python.org/dev/peps/pep-0002) 3. ''PEP'' 9, Sample Plaintext ''PEP'' Template, Warsaw (http://www.python.org/dev/peps/pep-0009) 4. ''PEP'' 12, Sample reStructuredText ''PEP'' Template, Goodger, Warsaw (http://www.python.org/dev/peps/pep-0012) {{{#!span id="id12" }}} 5. The script referred to here is pep2pyramid.py, the successor to pep2html.py, both of which live in the same directory in the hg repo as the PEPs themselves. Try pep2html.py --help for details. The URL for viewing PEPs on the web is http://www.python.org/dev/peps/. 6. http://bugs.python.org/ 7. http://www.opencontent.org/openpub/ 8. http://docutils.sourceforge.net/rst.html 9. http://docutils.sourceforge.net/ 10. http://hg.python.org/peps == Copyright #copyright This document has been placed in the public domain. -------8<------8<------8<------8<------8<------8<------8<------8<-------- -- Page URL: <https://issues.apache.org/bloodhound/wiki/Proposals> Apache Bloodhound <https://issues.apache.org/bloodhound/> The Apache Bloodhound (incubating) issue tracker This is an automated message. 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