anki/docs/contributing.md

Needs updating

Some of the below references the old build system, and needs updating.

Contributing Code

For info on contributing things other than code, such as translations, decks and add-ons, please see http://ankisrs.net/docs/manual.html#contributing

With most users now on 2.1, it's time to start paying down some of the technical debt that Anki's codebase has built up over the years. This is not an easy task - the code is tightly coupled together, not fully covered by unit tests, and mostly dynamically typed, meaning even small changes carry the risk of regressions.

At the moment, the focus is on changes that will make future maintenance and refactoring easier - migrating parts of the codebase to Rust, improving tooling and linting, type hints in the Python code, and more unit tests.

New features are not currently the top priority, unless they are easy wins as part of the refactoring process.

If you are planning to contribute any non-trivial changes, please reach out on the support site before you begin work. Some areas (primarily pylib/) are likely to change/conflict with other work, and larger changes will likely need to wait until the refactoring process nears completion.

Help wanted

If you'd like to contribute but don't know what to work on, please take a look at the issues on the following repo. It's quite bare at the moment, but will hopefully grow with time.

https://github.com/ankitects/help-wanted

Type hints

Type hints have recently been added to parts of the Python codebase, mainly using automated tools. At the moment, large parts of the codebase are still missing type hints, and some of the hints that do exist are incorrect or too general.

When running 'make check', Anki uses mypy to typecheck the code. Mypy mostly only checks functions that have type signatures, so adding more type signatures to the code increases the amount of code that mypy is able to analyze.

Patches that improve the type hints would be appreciated. And if you're adding new functionality, please use type hints in the new code you write where practical.

Parts of Anki's codebase use ad-hoc data structures like nested dictionaries and lists, and they can be difficult to fully type. Don't worry too much about getting the types perfect - even a partial type like Dict[str, Any] or List[Tuple] is an improvement over no types at all.

Anki bundles Qt stubs, but they are not perfect, so you'll find when doing things like connecting signals, you may have to add the following to the end of a line to silence the spurious errors.

 # type: ignore

In cases where you have two modules that reference each other, you can fix the import cycle by using fully qualified names in the types, and enabling annotations. For example, instead of

from aqt.browser import Browser

def myfunc(b: Browser) -> None:
  pass

use the following instead:

from __future__ import annotations

import aqt

def myfunc(b: aqt.browser.Browser) -> None:
  pass

Hooks

If you're writing an add-on and would like to extend a function that doesn't currently have a hook, a pull request that adds the required hooks would be welcome. If you could mention your use case in the pull request, that would be appreciated.

The hooks try to follow one of two formats:

[subject] [verb] - eg, note_type_added, card_will_render

[module] [verb] [subject] - eg, browser_did_change_row, editor_did_update_tags

The qt code tends to use the second form as the hooks tend to focus on particular screens. The pylib code tends to use the first form, as the focus is usually subjects like cards, notes, etc.

Using "did change" instead of the past test "changed" can seem awkward, but makes it consistent with "will", and is similar to the naming style used in iOS's libraries.

In most cases, hooks are better added in the GUI code than in pylib.

The hook code is automatically generated using the definitions in pylib/tools/genhooks.py and qt/tools/genhooks_gui.py. Adding a new definition in one of those files and running 'make develop' will update pylib/anki/hooks .py or qt/aqt/gui_hooks.py.

Translations

The translations into other languages will be fetched on the first build. If you'd like to keep them up to date, you need to run 'make pull-i18n' periodically.

For information on adding new translatable strings to Anki, please see https://ankitects.github.io/translating/#/anki/developers

Tests Must Pass

Please make sure 'make check' completes successfully before submitting code. You can do this automatically by adding the following into .git/hooks/pre-commit or .git/hooks/pre-push and making it executable.

#!/bin/bash set -eu -o pipefail ${SHELLFLAGS} make check

You may need to adjust the PATH variable so that things like a local install of cargo can be found.

If your change is to anki/ and not covered by the existing unit tests, please consider adding a unit test at the same time.

Code Style

You are welcome to use snake_case variable names and functions in newly introduced code, but please avoid renaming existing functions and global variables that use camelCaps. Variables local to a function are safer to rename, but please do so only when a function needs to be changed for other reasons as well.

Code formatting is automatically done when you use "make fix".

Do One Thing

A patch or pull request should be the minimum necessary to address one issue. Please don't make a pull request for a bunch of unrelated changes, as they are difficult to review and will be rejected - split them up into separate requests instead.

License

Please add yourself to the CONTRIBUTORS file in your first pull request.