Guidelines

Contributor Guidelines

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

• public mutable state
• global state
• implicit conversions
• threadLocal
• locks
• casting Also, be careful with introducing new, heavy external dependencies.

API design

• 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] (https://github.com/playframework/Play20/blob/master/framework/src/play/src/main/scala/play/api/cache/Cache.scala#L69))
  • 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
• Play is a Java and Scala framework, make sure your changes are working for both API-s

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 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