# Contributing to WTForms

WTForms is an open-source library and changing and evolving over time. To that end, we are supported by the contributions of many people in the python community.

## How to Contribute

WTForms is now on GitHub, so all contributions should be either associated with a pull request or with a ticket & patch.

## Contribution Guidelines

Code submitted should:

- Be formatted according to the PEP8 style guideline except that it does not need to confirm to the 79-column limit requirement of the guideline.

- Have tests

  - Unless it’s a bugfix, it should pass existing tests.

  - New classes or methods should mean new unit tests or extending existing tests.

  - Bugfixes can probably do with a regression test too (a test that would fail without this fix)

- Use naming schemes consistent with WTForms conventions

- Work on all versions of Python that WTForms currently supports. Take advantage of Github Actions for running tests on all supported Python versions.

## Note on API compatibility

WTForms is a very small library, but yet it’s possible to break API compatibility pretty easily. We are okay with breaking API compatibility for compelling features or major changes that we feel are worthwhile inclusions to the WTForms core, but realize that any API compatibility break will delay the inclusion of your ticket to the next major release.

Some examples of API compatibility breaks include:

- Adding new attributes or methods to the base Form class

- Modifying the number of required arguments of core methods like `process()`

- Changing the default behavior of a field.

However, it is still possible to add new features to WTForms without breaking API compatibility. For example, if one were looking to add Babel locale support to DecimalField, it could be done so long as by default, DecimalField behaved the same as it did before. This could look something like:

1. Add a keyword arg `use_locale` to the constructor

2. Make the keyword default to `False` so the behavior without this arg is identical to the previous behavior.

3. Add your functionality and make sure all existing DecimalField tests work unchanged (and of course add new tests for the new functionality).