SEP 0 — Purpose and Process#

Author:: Janko Slavič <janko.slavic@fs.uni-lj.si>
Status:: Active
Type:: Process
Created:: 2-Nov-2020

What is a SEP?#

SEP stands for SDyPy Enhancement Proposal. A SEP is a design document providing information to the SDyPy community, or describing a new feature for SDyPy or its processes or environment. The SEP should provide a concise technical specification of the feature and a rationale for the feature. SEPs follow the idea of NEPs (NumPy Enhancement Proposals) and PEPs (Python Enhancement Proposals).

Acknowledgement: this SEP heavily based on NEP0 (by Jarrod Millman <millman@berkeley.edu>)! Good practices from the Python ecosystem should be applied wherever possible!

We intend SEPs 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 SDyPy. The SEP author is responsible for building consensus within the community and documenting dissenting opinions.

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

Types#

There are three kinds of SEPs:

A Standards Track SEP describes a new feature or implementation for SDyPy.
An Informational SEP describes a SDyPy design issue, or provides general guidelines or information to the Python community, but does not propose a new feature. Informational SEPs do not necessarily represent a SDyPy community consensus or recommendation, so users and implementers are free to ignore Informational SEPs or follow their advice.
A Process SEP describes a process surrounding SDyPy, or proposes a change to (or an event in) a process. Process SEPs are like Standards Track SEPs but apply to areas other than the SDyPy language itself. They may propose an implementation, but not to SDyPy’s codebase; they require community consensus. Examples include procedures, guidelines, changes to the decision-making process, and changes to the tools or environment used in SDyPy development. Any meta-SEP is also considered a Process SEP.

SEP Workflow#

The SEP process begins with a new idea for SDyPy. It is highly recommended that a single SEP contain a single key proposal or new idea. Small enhancements or patches often don’t need a SEP and can be injected into the SDyPy development workflow with a pull request to the SDyPy repo. The more focused the SEP, the more successful it tends to be. If in doubt, split your SEP into several well-focused ones.

Each SEP must have a champion—someone who writes the SEP using the style and format described below, shepherds the discussions in the appropriate forums, and attempts to build community consensus around the idea. The SEP champion (a.k.a. Author) should first attempt to ascertain whether the idea is suitable for a SEP. Writting to the sdypy-discussion mailing list with the SEP tag is the best way to doing this mailing list.

The proposal should be submitted as a draft SEP via a GitHub pull request to the docs/seps directory with the name sep-<n>.rst where <n> is an appropriately assigned four-digit number (e.g., sep-0000.rst). The draft must use the :docs:`sep-template` file.

Once the PR for the SEP is in place, a post should be made to the mailing list containing the sections up to “Backward compatibility”, with the purpose of limiting discussion there to usage and impact. Discussion on the pull request will have a broader scope, also including details of implementation.

At the earliest convenience, the PR should be merged (regardless of whether it is accepted during discussion). Additional PRs may be made by the Author to update or expand the SEP, or by maintainers to set its status, discussion URL, etc.

Standards Track SEPs consist of two parts, a design document and a reference implementation. It is generally recommended that at least a prototype implementation be co-developed with the SEP, as ideas that sound good in principle sometimes turn out to be impractical when subjected to the test of implementation. Often it makes sense for the prototype implementation to be made available as PR to the SDyPy repo (making sure to appropriately mark the PR as a WIP).

Review and Resolution#

SEPs are discussed as issues SEP. The possible paths of the status of SEPs are as follows:

All SEPs should be created with the Draft status.

Eventually, after discussion, there may be a consensus that the SEP should be accepted – see the next section for details. At this point the status becomes Accepted.

Once a SEP 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.

To allow gathering of additional design and interface feedback before committing to long term stability for a language feature or standard library API, a SEP may also be marked as “Provisional”. This is short for “Provisionally Accepted”, and indicates that the proposal has been accepted for inclusion in the reference implementation, but additional user feedback is needed before the full design can be considered “Final”. Unlike regular accepted SEPs, provisionally accepted SEPs may still be Rejected or Withdrawn even after the related changes have been included in a Python release.

Wherever possible, it is considered preferable to reduce the scope of a proposal to avoid the need to rely on the “Provisional” status (e.g. by deferring some features to later SEPs), as this status can lead to version compatibility challenges in the wider NumPy ecosystem.

A SEP can also be assigned status Deferred. The SEP author or a core developer can assign the SEP this status when no progress is being made on the SEP.

A SEP 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 SEP author themselves has decided that the SEP is actually a bad idea, or has accepted that a competing proposal is a better alternative.

When a SEP is Accepted, Rejected, or Withdrawn, the SEP 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 thread in the mailing list archives.

SEPs can also be Superseded by a different SEP, rendering the original obsolete. The Replaced-By and Replaces headers should be added to the original and new SEPs respectively.

Process SEPs may also have a status of Active if they are never meant to be completed, e.g. SEP 0 (this SEP).

How a SEP becomes Accepted#

A SEP is Accepted by consensus of all interested contributors. We need a concrete way to tell whether consensus has been reached. When you think a SEP is ready to accept, send an email to the sdypy-discussion mailing list with a subject like:

Proposal to accept SEP #<number>: <title>

In the body of your email, you should:

link to the latest version of the SEP,
briefly describe any major points of contention and how they were resolved,
include a sentence like: “If there are no substantive objections within 7 days from this email, then the SEP will be accepted; see SEP 0 for more details.”

After you send the email, you should make sure to link to the email thread from the Discussion section of the SEP, so that people can find it later.

Generally the SEP author will be the one to send this email, but anyone can do it – the important thing is to make sure that everyone knows when a SEP is on the verge of acceptance, and give them a final chance to respond. If there’s some special reason to extend this final comment period beyond 7 days, then that’s fine, just say so in the email. You shouldn’t do less than 7 days, because sometimes people are travelling or similar and need some time to respond.

In general, the goal is to make sure that the community has consensus, not provide a rigid policy for people to try to game. When in doubt, err on the side of asking for more feedback and looking for opportunities to compromise.

If the final comment period passes without any substantive objections, then the SEP can officially be marked Accepted. You should send a followup email notifying the list (celebratory emoji optional but encouraged 🎉✨), and then update the SEP by setting its :Status: to Accepted, and its :Resolution: header to a link to your followup email.

If there are substantive objections, then the SEP remains in Draft state, discussion continues as normal, and it can be proposed for acceptance again later once the objections are resolved.

In unusual cases, the SDyPy Steering Council may be asked to decide whether a controversial SEP is Accepted.

Maintenance#

In general, Standards track SEPs are no longer modified after they have reached the Final state as the code and project documentation are considered the ultimate reference for the implemented feature. However, finalized Standards track SEPs may be updated as needed.

Process SEPs 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 NEP being updated.

Format and Template#

SEPs are UTF-8 encoded text files using the reStructuredText format. Please see the SEP X — Template and Instructions file and the reStructuredTextPrimer for more information. We use Sphinx to convert SEPs to HTML for viewing on the web [2].

Header Preamble#

Each SEP must begin with a header preamble. The headers must appear in the following order. Headers marked with * are optional. All other headers are required.

  :Author: <list of authors' real names and optionally, email addresses>
  :Status: <Draft | Active | Accepted | Deferred | Rejected |
           Withdrawn | Final | Superseded>
  :Type: <Standards Track | Process>
  :Created: <date created on, in dd-mmm-yyyy format>
* :Requires: <sep numbers>
* :SDyPy-Version: <version number>
* :Replaces: <sep number>
* :Replaced-By: <sep number>
* :Resolution: <url>

The Author header lists the names, and optionally the email addresses of all the authors of the SEP. 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. If there are multiple authors, each should be on a separate line.