Drush\Runtime
Classes
Prepare our Dependency Injection Container
Log PHP errors to the Drush log. This is in effect until Drupal's error handler takes over.
Find drush.services.yml files.
Use the Symfony Dependency Injection Container to instantiate services.
The RedispatchHook is installed as an init hook that runs before all commands. If the commandline contains an alias or a site specification that points at a remote machine, then we will stop execution of the current command and instead run the command remotely.
Control the Drush runtime environment
Manage Drush services.
Drush's shutdown handler
The TildeExpansionHook is installed as a preValidate hook that runs before all commands. Argument or option values containing a leading tilde will be expanded to an absolute path.
Interfaces
HandlerInterface represents a PHP system handler (e.g. the error reporting handler, the shutdown handler) that may be globally installed.