In Symfony 3.3 you can define your own YAML tags, which are mostly used to define explicit data types.
Symfony 3.3 adds support for "getter autowiring" in PHP 7 applications to improve the RAD features available for Symfony applications.
Symfony 3.3 containers implement a standard called "PSR-11: Container Interface" to increase application interoperability.
In Symfony 3.3 we decided to enable automatic console logging, so you'll get log messages when an exception occurs during the execution of a command and when the exit status of the command is different than 0.
Symfony 3.3 adds a new simpler cache based on the PSR-16 standard that complements the existing PSR-6 based cache mechanism and it's optimized to store, fetch and remove items from a cache as easy as possible.
Symfony 3.3 includes a new component called Dotenv to parse and load .env files that define environment variables for your applications.
In Symfony 3.3, the DependencyInjection component has deprecated the possibility of dumping an uncompiled container, the DefinitionDecorator class and the case-insensitivity of service identifiers.
In Symfony 3.3, we added a new Cache adapter for Memcached servers.
In Symfony 3.3, the contents dumped with the "dump()" function include a local search box to help you find any value hidden deep inside complex dumps.
In Symfony 3.3, the "class" argument of the services is now optional. When it's undefined, Symfony considers that the "id" of the service is the PHP class.