§Contributor Guidelines

Implementation-wise, the following things should be avoided as much as possible:

• public mutable state
• global state
• implicit conversions
• threadLocal
• locks
• casting
• introducing new, heavy external dependencies

§API design

• Play is a Java and Scala framework, make sure your changes are working for both API-s
• Java APIs should go to framework/play/src/main/java, package structure is play.myapipackage.xxxx
• Scala APIs should go to framework/play/src/main/scala, where the package structure is play.api.myapipackage
• Java and Scala APIs should be implemented the following way:
• implement the core API in scala (play.api.xxx)
• if your component requires life cycle management or needs to be swappable, create a plugin, otherwise skip this step
• wrap core API for scala users (example)
• wrap scala API for java users (example)
• features are forever, always think about whether a new feature really belongs to the core framework or it should be implemented as a plugin
• if you are in doubt, ask on the mailing list

§Testing and documentation

• each and every public facing method and class need to have a corresponding scaladoc or javadoc with examples, description etc.
• each feature and bug fix requires either a functional test (framework/integrationtest) or a spec (/play/src/test)
• run Play’s integration test suite framework/runtests before pushing. If a test fails, fix it, do not ignore it.

§source format

• run scalariform-format before commit

§git commits

• prefer rebase
• bigger changesets