What is a PSEP?

PSEP stands for PySide Enhancement Proposal. A PSEP is a design document providing information to the PySide community, or describing a new feature for PySide or its processes or environment. The PSEP should provide a concise technical specification of the feature and a rationale for the feature.

We intend PSEPs to be the primary mechanisms for proposing new features, for collecting community input on an issue, and for documenting the design decisions that have gone into PySide. The PSEP author is responsible for building consensus within the community and documenting dissenting opinions.

Because the PSEPs are maintained as text files in a versioned repository, their revision history is the historical record of the feature proposal [1].

The whole PSEP process has been copied verbatim from Python's PEP (Python Enhancement Proposal) process, and this document has been adapted to PSEP by Matti Airas from PEP 1 by Barry Warsaw, Jeremy Hylton, and David Goodger.

PSEP Types

There are three kinds of PSEP:

1. A Standards Track PSEP describes a new feature or implementation for PySide.
2. An Informational PSEP describes a PySide design issue, or provides general guidelines or information to the PySide community, but does not propose a new feature. Informational PSEPs do not necessarily represent a PySide community consensus or recommendation, so users and implementors are free to ignore Informational PSEPs or follow their advice.
3. A Process PSEP describes a process surrounding PySide, or proposes a change to (or an event in) a process. Process PSEPs are like Standards Track PSEPs but apply to areas other than the PySide itself. They may propose an implementation, but not to PySide's codebase; they often require community consensus; unlike Informational PSEPs, 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-PSEP is also considered a Process PSEP.

PSEP Work Flow

The PSEP editors assign PSEP numbers and change their status. The current PSEP editor is Matti Airas. Please send all PSEP-related email to <pyside@lists.openbossa.org> (no cross-posting please). Also see PSEP Editor Responsibilities & Workflow below.

The PSEP process begins with a new idea for PySide. It is highly recommended that a single PSEP contain a single key proposal or new idea. The more focussed the PSEP, the more successful it tends to be. The PSEP editor reserves the right to reject PSEP proposals if they appear too unfocussed or too broad. If in doubt, split your PSEP into several well-focussed ones.

Each PSEP must have a champion -- someone who writes the PSEP using the style and format described below, shepherds the discussions in the appropriate forums, and attempts to build community consensus around the idea. The PSEP champion (a.k.a. Author) should first attempt to ascertain whether the idea is PSEP-able. Posting to the pyside@lists.openbossa.org mailing list is recommended. Enhancements not resulting in API changes usually don't need a PSEP and can be injected into the PySide development work flow with a patch submission to the PySide issue tracker [4].

The PSEP champion then emails the PSEP editor <pyside@lists.openbossa.org> with a proposed title and a rough, but fleshed out, draft of the PSEP. This draft must be written in PSEP style as described below.

If the PSEP editor approves, he will assign the PSEP a number, label it as Standards Track, Informational, or Process, give it status "Draft", and create and check-in the initial draft of the PSEP. The PSEP editor will not unreasonably deny a PSEP. Reasons for denying PSEP status include duplication of effort, being technically unsound, not providing proper motivation or addressing backwards compatibility, or not in keeping with the PySide philosophy. The TBC (Temporary Benevolent Committee, consisting of the core dev team and Matti Airas) can be consulted during the approval phase, and is the final arbiter of the draft's PSEP-ability.

If a pre-PSEP is rejected, the author may elect to take the pre-PSEP to the pyside@lists.openbossa.org mailing list to help flesh it out, gain feedback and consensus from the community at large, and improve the PSEP for re-submission.

The author of the PSEP is then responsible for posting the PSEP to the community forums, and marshaling community support for it. As updates are necessary, the PSEP author can check in new versions if they have SVN commit permissions, or can email new PSEP versions to the PSEP editor for committing.

Standards Track PSEPs consist of two parts, a design document and a reference implementation. The PSEP should be reviewed and accepted before a reference implementation is begun, unless a reference implementation will aid people in studying the PSEP. Standards Track PSEPs must include an implementation -- in the form of code, a patch, or a URL to same -- before it can be considered Final.

PSEP authors are responsible for collecting community feedback on a PSEP before submitting it for review. A PSEP that has not been discussed on pyside@lists.openbossa.org will not be accepted. 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 PSEP author accept private comments in the early design phases, setting up a wiki page, etc. PSEP authors should use their discretion here.

Once the authors have completed a PSEP, they must inform the PSEP editor that it is ready for review. PSEPs are reviewed by the TBC, who may accept or reject a PSEP or send it back to the author(s) for revision. For a PSEP that is pre-determined to be acceptable (e.g., it is an obvious win as-is and/or its implementation has already been checked in) the TBC may also initiate a PSEP review, first notifying the PSEP author(s) and giving them a chance to make revisions.

For a PSEP 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 properly balance the "pythonicity" and "Qt-likeness" in order to be accepted by the TBC. (However, "pythonic" and "Qt-likeness" are imprecise terms; they may be defined as whatever is acceptable to the TBC. This logic is intentionally circular.)

Once a PSEP has been accepted, the reference implementation must be completed. When the reference implementation is complete and accepted by the TBC, the status will be changed to "Final".

A PSEP can also be assigned status "Deferred". The PSEP author or editor can assign the PSEP this status when no progress is being made on the PSEP. Once a PSEP is deferred, the PSEP editor can re-assign it to draft status.

A PSEP 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.

PSEPs can also be replaced by a different PSEP, rendering the original obsolete. This is intended for Informational PSEPs, where version 2 of an API can replace version 1.

The possible paths of the status of PSEPs are as follows:

Some Informational and Process PSEPs may also have a status of "Active" if they are never meant to be completed. E.g. PSEP 1 (this PSEP).

What belongs in a successful PSEP?

Each PSEP should have the following parts:

1. Preamble -- RFC 822 style headers containing meta-data about the PSEP, including the PSEP 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 PSEP must either be explicitly labelled as placed in the public domain (see this PSEP as an example) or licensed under the Open Publication License [5].

4. Specification -- The technical specification should describe the syntax and semantics of any new API feature. The specification should be detailed enough to allow competing, interoperable implementations for any of the current Python Qt bindings.

5. Motivation -- The motivation is critical for PSEPs that want to change the PySide API. It should clearly explain why the existing API is inadequate to address the problem that the PSEP solves. PSEP 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 PSEPs that introduce backwards incompatibilities must include a section describing these incompatibilities and their severity. The PSEP must explain how the author proposes to deal with these incompatibilities. PSEP submissions without a sufficient backwards compatibility treatise may be rejected outright.

8. Reference Implementation -- The reference implementation must be completed before any PSEP is given status "Final", but it need not be completed before the PSEP 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 PySide API reference or the respective generator tool reference.

PSEP Formats and Templates

As opposed to PEP, there is only one PSEP format available to authors: reStructuredText [6]. ReStructuredText [6] PSEPs allow for rich markup that is still quite easy to read, but results in much better-looking and more functional HTML. PSEP 12 contains instructions and a template [2] for reStructuredText PSEPs.

There is a Python script that converts PSEPs to HTML for viewing on the web [3]. reStructuredText PSEPs are parsed and converted by Docutils [7] code called from the script.

PSEP Header Preamble

Each PSEP must begin with an 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.

  PSEP: <psep number>
  Title: <psep title>
  Last-Modified: <svn date string>
  Author: <list of authors' real names and optionally, email addrs>
* Discussions-To: <email address>
  Status: <Draft | Active | Accepted | Deferred | Rejected |
           Withdrawn | Final | Replaced>
  Type: <Standards Track | Informational | Process>
* Content-Type: <text/plain | text/x-rst>
* Requires: <psep 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: <psep number>
* Replaced-By: <psep number>

The Author header lists the names, and optionally the email addresses of all the authors/owners of the PSEP. The format of the Author header value must be

Random J. User <address@dom.ain>

if the email address is included, and just

Random J. User

if the address is not given. New PSEPs must use the mandated format above.

If there are multiple authors, each should be on a separate line following RFC 2822 continuation line conventions. Note that personal email addresses in PSEPs will be obscured as a defense against spam harvesters.

While a PSEP is in private discussions (usually during the initial Draft phase), a Discussions-To header will indicate the mailing list or URL where the PSEP is being discussed. No Discussions-To header is necessary if the PSEP is being discussed privately with the author, or on the pyside@lists.openbossa.org mailing list. Note that email addresses in the Discussions-To header will not be obscured.

The Type header specifies the type of PSEP: Standards Track, Informational, or Process.

The format of a PSEP is specified with a Content-Type header. The only acceptable values is "text/x-rst" for reStructuredText PSEPs (see PSEP 12 [2]).

The Created header records the date that the PSEP was assigned a number, while Post-History is used to record the dates of when new versions of the PSEP are posted to python-list and/or python-dev. Both headers should be in dd-mmm-yyyy format, e.g. 14-Aug-2001.

TODO: How should we deal with different Python, Qt, and PySide versions?

Standards Track PSEPs must have a Python-Version header which indicates the version of Python that the feature will be released with. Informational and Process PSEPs do not need a Python-Version header.

PSEPs may have a Requires header, indicating the PSEP numbers that this PSEP depends on.

PSEPs may also have a Replaced-By header indicating that a PSEP has been rendered obsolete by a later document; the value is the number of the PSEP that replaces the current document. The newer PSEP must have a Replaces header containing the number of the PSEP that it rendered obsolete.

Auxiliary Files

PSEPs may include auxiliary files such as diagrams. Such files must be named psep-XXXX-Y.ext, where "XXXX" is the PSEP number, "Y" is a serial number (starting at 1), and "ext" is replaced by the actual file extension (e.g. "png").

Reporting PSEP Bugs, or Submitting PSEP Updates

How you report a bug, or submit a PSEP update depends on several factors, such as the maturity of the PSEP, the preferences of the PSEP author, and the nature of your comments. For the early draft stages of the PSEP, it's probably best to send your comments and changes directly to the PSEP author. For more mature, or finished PSEPs you may want to submit corrections to the PySide issue tracker [4] so that your changes don't get lost. If the PSEP author is a PySide developer, assign the bug/patch to him, otherwise assign it to the PSEP editor.

When in doubt about where to send your changes, please check first with the PSEP author and/or PSEP editor.

PSEP authors who have write permissions to the Gitorious repository can push the changes to the repository themselves.

Transferring PSEP Ownership

It occasionally becomes necessary to transfer ownership of PSEPs to a new champion. In general, we'd like to retain the original author as a co-author of the transferred PSEP, 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 PSEP 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 PSEP. We try to build consensus around a PSEP, but if that's not possible, you can always submit a competing PSEP.

If you are interested in assuming ownership of a PSEP, send a message asking to take over, addressed to both the original author and the PSEP editor <pyside@lists.openbossa.org>. If the original author doesn't respond to email in a timely manner, the PSEP editor will make a unilateral decision (it's not like such decisions can't be reversed :).

PSEP Editor Responsibilities & Workflow

A PSEP editor must subscribe to the <pyside@lists.openbossa.org> list. All PSEP-related correspondence should be sent (or CC'd) to <pyside@lists.openbossa.org> (but please do not cross-post!).

For each new PSEP that comes in an editor does the following:

• Read the PSEP 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 PSEP for language (spelling, grammar, sentence structure, etc.), markup (for reST PSEPs), code style (examples should match PSEP 8 & 7).

If the PSEP isn't ready, the editor will send it back to the author for revision, with specific instructions.

Once the PSEP is ready for the repository, the PSEP editor will:

• Assign a PSEP number (almost always just the next available number, but sometimes it's a special/joke number, like 666 or 3141).
• List the PSEP in PSEP 0 (in two places: the categorized list, and the numeric list).
• Add the PSEP to the Git repository. To clone a copy of the Git repository, see the PySide Gitorious page.
• Monitor python.org to make sure the PSEP gets added to the site properly.
• Send email back to the PSEP author with next steps (post to pyside@lists.openbossa.org).

Updates to existing PSEPs also come in to pyside@lists.openbossa.org. Alternatively, Gitorious merge requests may be made directly.

Many PSEPs are written and maintained by developers with write access to the PySide repository. The PSEP editors monitor the repository PSEP changes, and correct any structure, grammar, spelling, or markup mistakes we see.

The editors don't pass judgement on PSEPs. We merely do the administrative & editorial part. Except for times like this, there's relatively low volume.

References and Footnotes

Copyright

This document has been placed in the public domain.