novelWriter/CONTRIBUTING.md

Contributing Guide

When contributing to this repository, please first discuss the change you wish to make via the issue tracker with the owner of this repository before making a change. If you just want to make a minor correction, like fix a typo or similar, feel free to just make a pull request directly.

There is a code of conduct. Please follow it in all your interactions with the project.

Pull Request Process

1. Make sure your code passes all tests and conforms to the style guide. You can check that the code conforms by running flake8 from the root of the project folder.
2. Please provide a complete description of the changes in the pull request, and a summary that can be copied into the CHANGELOG. Remember to reference any issue related by providing the issue number.
3. Do not change the version number unless asked to do so. Version numbers are bumped in separate release pull requests by the maintainer.

Code of Conduct

Our Pledge

In the interest of fostering an open and welcoming environment, we as contributors and maintainers pledge to making participation in our project and our community a harassment-free experience for everyone, regardless of age, body size, disability, ethnicity, gender identity and expression, level of experience, nationality, personal appearance, race, religion, or sexual identity and orientation.

Please see the CODE_OF_CONDUCT file for the full text.

Code Style Guide

The source code of novelWriter broadly follows the PEP8 style guide , but with a few modifications and exceptions.

Line Length

For this project, source lines should stay within the 79 and 99 character limits described by PEP8. 79 characters is often too restrictive, so 99 character lines are acceptable when that is more practical. Readability has priority. Generally, if a code statement requires multiple lines, the lines should wrap at 79 characters, not 99. If wrapping can be avoided by going to 99, then that is preferrable.

For text files, the text should also be wrapped at 99 character. The exception is markdown image tags and urls.

Please do not submit PRs that re-wrap existing source or text unless this has been discussed beforehand.

Linting with flake8

An excellent tool for checking Python code for errors and coding style is flake8. The documentation is available here.

The setup.cfg file in the root of this project has the following settings:

[flake8]
ignore = E203,E221,E226,E228,E241,E251,E261,E266,E302,E305
max-line-length = 99
exclude = docs/*

The command line equivalent, with reporting, is:

flake8 . --count --ignore E203,E221,E226,E228,E241,E251,E261,E266,E302,E305 --max-line-length=99 --show-source --statistics

Passing this check is required before contributions are merged into the main branch. This is checked automatically when you make a pull request. You can run the flake8 command locally to check beforehand. The full command will give you a detailed description of the code lines that do not conform to the standard.

Ignored Errors

Some errors are ignored in novelWriter, for various reasons. In addition, novelWriter uses camelCase function and variable names due to this being the standard for the Qt libraries, and also because of the author's personal preferences.

The reason behind the other ignored error codes are listed below. Many of them are due to PEP8 not permitting column alignment as opposed to many other coding styles. I find them useful in regions of bulk value assignments. There's a reason why tables are more readable than lists. They should be used sparingly though.

The ignored errors are all pycodestyle errors, and they are documented here.

My main objection to PEP8 is the universal rejection of column alignment of blocks of code. In particular when assigning variables and populating dictionaries. The PEP8 rule stands in contrast to conventions from other code styles, like for Go. I have always used column alignment to a certain degree in all programming languages I use, and I firmly believe it improves readability, but should not be overused.

E203: whitespace before ‘:’
Reason: Column alignment.

E221: multiple spaces before operator
Reason: Column alignment.

E226: missing whitespace around arithmetic operator
Reason: This doesn't actually follow the PEP8 recommendation of grouping longer equations by operator precedence like 2*a + 3*b instead of a * a + 3 * b. Generally, don't use spaces around *, / and **, but do use spaces around + and -. For appending strings, the spaces can be dropped. Don't use the + operator for appending multiple strings. Use formatting instead.

E228 missing whitespace around modulo operator
Reason: See reason for E226. Formatting % like / and * should be possible.

E241: multiple spaces after ‘,’
Reason: Column alignment.

E251: unexpected spaces around keyword / parameter equals
Reason: Column alignment.

E261: at least two spaces before inline comment
Reason: With syntax highlighting, this one doesn't make much sense.

E266: too many leading ‘#’ for block comment
Reason: In the source multiple #s is sometimes used to indicate importance or heading level, like markdown headers.

E302: expected 2 blank lines, found 0
Reason: Applies to classes. Instead, end classes with a comment like # END Class ClassName to make it easier to see which class just ended. The double line break is then redundant.

E305: expected 2 blank lines after end of function or class
Reason: Instead, always end a function with a return, preferably indented at function level. The end of the function is then clear.