CEP 6 - Cyclus Pull Request Style Guide

Title:Cyclus Pull Request Style Guide
Author:Matthew Gidden


There is a strong motivation for summarizing and enumerating feature additions, bug fixes, and other changes to the code base. Through use of an agreed-upon format and style, tools for aggregating and categorizing changes can be developed. While this strategy may be applied to issues, this CEP is related to pull requests (PRs) only.

A canoncial class of top-level labels is proposed. The purpose of these labels is to broadly categorize additions to the code base. Then, a minimum style guide is proposed to provide a known, queryable structure to the body of each pull request.


Every PR must be assigned at least one label from the following set:

  • Feature - Release Notes
  • Feature
  • Bug Fix
  • Maintenance
  • Other

While a PR may have any number of other descriptive labels, it is considered blocked if it does not have (at minimum) one of the above labels.

A PR may be labeled as Feature - Release Notes by either the author or reviewer. If there is a disagreement between the two parties, deference is given to the party who prefers the Feature - Release Notes tag. A PR with this label is provided candidacy for inclusion in the release notes (highlighting the feature addition) but does not guaranteed inclusion in the release notes. The release manager is provided deference in making the decision of what features to highlight in the release notes, per CEP 3.


Any PR must have, at minimum, a succinct summary of its associated changes. This summary must be present at the top of the PR body and must be followed by a new line. A PR is considered blocked if it does comply with this structure.

Any additional structure, while clarifying, is optional.


The following provides an example of the raw markdown associated with an existing PR:

Added simple buy and sell inventory policies

Inventory policies were added that automate simplistic interactions with the
DRE. Each policy is assigned to a `ResBuf` instance and implements the `Trader`
interface. They can be initialized with information regarding the commodities to
be bought or sold as well as a maximum per-timestep throughput. Purchasing
inventory policies also support `(S, s)` behavior, noted in supply chain literature. [1]

[1] Zheng, Yu-Sheng. "A simple proof for optimality of (s, S) policies in
infinite-horizon inventory systems." Journal of Applied Probability
(1991): 802-810.

Related Issues
* closes #1047
* related to cyclus/cycamore#318


Using the Github API either directly or through a module like github3.py in conjunction with a standard style can allow for the automation of otherwise repetitive and time consuming tasks. A chief use case is the generation of release notes. Specifically, if every PR that enables a major and minor feature can be identified and a summary statement extracted, then the task of writing release notes becomes much simpler. This proposal enables such tools to be constructed and utilized.

Backwards Compatibility

Closed PRs are archival documents whereas a codebase is a living “document”. Accordingly, while one would expect a code style guide to be applicable upon acceptance to the entire code base, this style guide to only be applicable to open PRs. Closed PR text cannot be edited such that it no longer complies with the document structure listed in the Layout section. Additional comments on closed PRs encouraged as they are needed.

Document History

This document is released under the CC-BY 3.0 license.