# Contributing docs

We use Sphinx to generate our docs website. You can trigger the process locally by executing:

>     $ make doc

It is also integrated with Read The Docs that builds and publishes each commit to the main branch and generates live docs previews for each pull request.

The sources of the Sphinx documents use reStructuredText as a de-facto standard. But in order to make contributing docs more beginner-friendly, we’ve integrated MyST parser allowing us to also accept new documents written in an extended version of Markdown that supports using Sphinx directives and roles. Read the docs to learn more on how to use it.

## Adding change notes with your PRs

It is very important to maintain a log for news of how updating to the new version of the software will affect end-users. This is why we enforce collection of the change fragment files in pull requests as per Towncrier philosophy.

The idea is that when somebody makes a change, they must record the bits that would affect end-users only including information that would be useful to them. Then, when the maintainers publish a new release, they’ll automatically use these records to compose a change log for the respective version. It is important to understand that including unnecessary low-level implementation related details generates noise that is not particularly useful to the end-users most of the time. And so such details should be recorded in the Git history rather than a changelog.

## Alright! So how to add a news fragment?

`yarl` uses towncrier for changelog management. To submit a change note about your PR, add a text file into the `CHANGES/` folder. It should contain an explanation of what applying this PR will change in the way end-users interact with the project. One sentence is usually enough but feel free to add as many details as you feel necessary for the users to understand what it means.

Use the past tense for the text in your fragment because, combined with others, it will be a part of the “news digest” telling the readers what changed in a specific version of the library since the previous version. You should also use reStructuredText syntax for highlighting code (inline or block), linking parts of the docs or external sites. However, you do not need to reference the issue or PR numbers here as towncrier will automatically add a reference to all of the affected issues when rendering the news file. If you wish to sign your change, feel free to add `-- by :user:`github-username`` at the end (replace `github-username` with your own!).

Finally, name your file following the convention that Towncrier understands: it should start with the number of an issue or a PR followed by a dot, then add a patch type, like `feature`, `doc`, `contrib` etc., and add `.rst` as a suffix. If you need to add more than one fragment, you may add an optional sequence number (delimited with another period) between the type and the suffix.

In general the name will follow `<pr_number>.<category>.rst` pattern, where the categories are:

- `bugfix`: A bug fix for something we deemed an improper undesired behavior that got corrected in the release to match pre-agreed expectations.

- `feature`: A new behavior, public APIs. That sort of stuff.

- `deprecation`: A declaration of future API removals and breaking changes in behavior.

- `breaking`: When something public gets removed in a breaking way. Could be deprecated in an earlier release.

- `doc`: Notable updates to the documentation structure or build process.

- `packaging`: Notes for downstreams about unobvious side effects and tooling. Changes in the test invocation considerations and runtime assumptions.

- `contrib`: Stuff that affects the contributor experience. e.g. Running tests, building the docs, setting up the development environment.

- `misc`: Changes that are hard to assign to any of the above categories.

A pull request may have more than one of these components, for example a code change may introduce a new feature that deprecates an old feature, in which case two fragments should be added. It is not necessary to make a separate documentation fragment for documentation changes accompanying the relevant code changes.

## Examples for adding changelog entries to your Pull Requests

File `CHANGES/603.removal.1.rst`:

    Dropped Python 3.5 support; Python 3.6 is the minimal supported Python
    version -- by :user:`webknjaz`.

File `CHANGES/550.bugfix.rst`:

    Started shipping Windows wheels for the x86 architecture
    -- by :user:`Dreamsorcerer`.

File `CHANGES/553.feature.rst`:

    Added support for ``GenericAliases`` (``MultiDict[str]``) under Python 3.9
    and higher -- by :user:`mjpieters`.

Tip

See `towncrier.toml` for all available categories (`tool.towncrier.type`).