In Symfony 3.2, we decided to augment the YAML format with a custom extension to support PHP constants. This feature provides feature parity with other configuration formats, such as XML.
Symfony 3.2 adds a new helper method to the base controller called file(). Its purpose is to simplify serving binary files.
The Cache component is a strict implementation of the PSR-6: Caching Interface standard. You can use it to cache arbitrary content in your application and some Symfony components use it internally to improve their performance.