Drupal's service container for dependency injection allows modules to register services and parameters to the service container or alter and modify the service container.

Last week I wrote about dependency injection anti-patterns in Drupal. These anti-patterns occur when your service's constructor has logic that interacts with the injected dependent services beyond assigning them to properties.

Whenever I have done an audit for a Drupal codebase, one of the first things I manually review and profile is dependency injection anti-patterns in custom code and any contributed modules used. The anti-pattern isn't for accessing services statically through \Drupal: service. These anti-patterns live within the class's __construct method.