Sifis-Home WP2 RFCs

This RFC model is based on that provided by the Rust Team.

New features, ideas and improvements can be implemented and reviewed via the normal GitHub pull request workflow.

The "RFC" (request for comments) process is intended to provide a consistent and controlled path for new features to enter the project, so that all stakeholders can be confident about the direction the project is evolving in.

Table of Contents

Before creating an RFC

A hastily-proposed RFC can hurt its chances of acceptance. Low quality proposals, proposals for previously-rejected features, or those that don't fit into the near-term roadmap, may be quickly rejected, which can be demotivating for the unprepared contributor. Laying some groundwork ahead of the RFC can make the process smoother.

Although there is no single way to prepare for submitting an RFC, it is generally a good idea to pursue feedback from other project developers beforehand, to ascertain that the RFC may be desirable; having a consistent impact on the project requires concerted effort toward consensus-building.

The most common preparations for writing and submitting an RFC include talking the idea over on our official Zulip server, then file issues on this repo for a more specific discussion.

What the process is

In short, to get a major feature added to Rust, one must first get the RFC merged into the RFC repository as a markdown file. At that point the RFC is "active" and may be implemented with the goal of eventual inclusion into Rust.

  • Fork the RFC repo RFC repository
  • Create a branch named as the feature you want to create (e.g my-feature).
  • Copy 0000-template.md to text/0000-my-feature.md (where "my-feature" is descriptive). Don't assign an RFC number yet; This is going to be the PR number and we'll rename the file accordingly if the RFC is accepted.
  • Fill in the RFC. Put care into the details: RFCs that do not present convincing motivation, demonstrate lack of understanding of the design's impact, or are disingenuous about the drawbacks or alternatives tend to be poorly-received.
  • Submit a pull request. As a pull request the RFC will receive design feedback from the community, and the author should be prepared to revise it in response.
  • Now that your RFC has an open pull request, use the issue number of the PR to update your 0000- prefix to that number.
  • The working package members and other interested parties will discuss the RFC pull request, as much as possible in the pull request itself.
  • RFCs rarely go through this process unchanged, especially as alternatives and drawbacks are shown. You can make edits, big and small, to the RFC to clarify or change the design, but make changes as new commits to the pull request, and leave a comment on the pull request explaining your changes. Specifically, do not squash or rebase commits after they are visible on the pull request.
  • At some point, a member of the working package will propose a "motion for final comment period" (FCP), along with a disposition for the RFC (merge, close, or postpone).
    • This step is taken when enough of the tradeoffs have been discussed that the working package team are in a position to make a decision. That does not require consensus amongst all participants in the RFC thread (which is usually impossible). However, the argument supporting the disposition on the RFC needs to have already been clearly articulated, and there should not be a strong consensus against that position outside of the working package team. Working package members use their best judgment in taking this step, and the FCP itself ensures there is ample time and notification for stakeholders to push back if it is made prematurely.
    • For RFCs with lengthy discussion, the motion to FCP is usually preceded by a summary comment trying to lay out the current state of the discussion and major tradeoffs/points of disagreement.
    • Before actually entering FCP, all members of the working package team must sign off; this is often the point at which many working package members first review the RFC in full depth.
  • The FCP lasts ten calendar days, so that it is open for at least 5 business days. It is also advertised widely. This way all stakeholders have a chance to lodge any final objections before a decision is reached.
  • In most cases, the FCP period is quiet, and the RFC is either merged or closed. If a RFC is accepted, before merging it, the label approved-rfc MUST be added to the PR in order to stop the CI rendering the RFC. However, sometimes substantial new arguments or ideas are raised, the FCP is canceled, and the RFC goes back into development mode.

The RFC life-cycle

To be decided

Reviewing RFCs

To be decided

Implementing an RFC

Some accepted RFCs represent vital features that need to be implemented right away. Other accepted RFCs can represent features that can wait until some arbitrary developer feels like doing the work.

The author of an RFC is not obligated to implement it. Of course, the RFC author (like any other developer) is welcome to post an implementation for review after the RFC has been accepted.

If you are interested in working on the implementation for an "active" RFC, but cannot determine if someone else is already working on it, feel free to ask (e.g. by leaving a comment on the associated issue).

RFC Postponement

Some RFC pull requests are tagged with the "postponed" label when they are closed (as part of the rejection process). An RFC closed with "postponed" is marked as such because we want neither to think about evaluating the proposal nor about implementing the described feature until some time in the future, and we believe that we can afford to wait until then to do so. Postponed pull requests may be re-opened when the time is right.

Usually an RFC pull request marked as "postponed" has already passed an informal first round of evaluation, namely the round of "do we think we would ever possibly consider making this change, as outlined in the RFC pull request, or some semi-obvious variation of it." (When the answer to the latter question is "no", then the appropriate response is to close the RFC, not postpone it.)

License

To be decided

Contributions

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you shall be licensed as above, without any additional terms or conditions.

Summary

One paragraph explanation of the feature.

Motivation

Why are we doing this? What use cases does it support? What is the expected outcome?

Guide-level explanation

Explain the proposal as if it was already approved and you were teaching it to another person. That generally means:

  • Introducing new named concepts.
  • Explaining the feature largely in terms of examples.

Reference-level explanation

This is the technical portion of the RFC. Explain the design in sufficient detail that:

  • Its interaction with other features is clear.
  • It is reasonably clear how the feature would be implemented.
  • Corner cases are dissected by example.

The section should return to the examples given in the previous section, and explain more fully how the detailed proposal makes those examples work.

Drawbacks

Why should we not do this?

Rationale and alternatives

  • Why is this design the best in the space of possible designs?
  • What other designs have been considered and what is the rationale for not choosing them?
  • What is the impact of not doing this?

Prior art

Discuss prior art, both the good and the bad, in relation to this proposal. A few examples of what this can include are:

  • For community proposals: Is this done by some other community and what were their experiences with it?
  • For other teams: What lessons can we learn from what other communities have done here?
  • Papers: Are there any published papers or great posts that discuss this? If you have some relevant papers to refer to, this can serve as a more detailed theoretical background.

This section is intended to encourage you as an author to think about the lessons from other projects, provide readers of your RFC with a fuller picture. If there is no prior art, that is fine - your ideas are interesting to us whether they are brand new or if it is an adaptation from other projects.

Unresolved questions

  • What parts of the design do you expect to resolve through the RFC process before this gets merged?
  • What parts of the design do you expect to resolve through the implementation of this feature before stabilization?
  • What related issues do you consider out of scope for this RFC that could be addressed in the future independently of the solution that comes out of this RFC?

Future possibilities

Think about what the natural extension and evolution of your proposal would be and how it would affect the project as a whole in a holistic way. Try to use this section as a tool to more fully consider all possible interactions with the project in your proposal. Also consider how this all fits into the roadmap for the project and of the relevant sub-team.

This is also a good place to "dump ideas", if they are out of scope for the RFC you are writing but otherwise related.

If you have tried and cannot think of any future possibilities, you may simply state that you cannot think of anything.

Note that having something written down in the future-possibilities section is not a reason to accept the current or a future RFC; such notes should be in the section on motivation or rationale in this or subsequent RFCs. The section merely provides additional information.