This commit adds `AbstractController.deprecator` and
`ActionController.deprecator`, and replaces all usages of
`ActiveSupport::Deprecation.warn` in `actionpack/lib/action_controller`
with the latter.
Additionally, this commit adds `ActionController.deprecator` to
`Rails.application.deprecators`. Because `AbstractController` does not
have its own railtie to do the same, `AbstractController` and
`ActionController` use the same deprecator instance. Thus, both can be
configured via `Rails.application.deprecators[:action_controller]` or
via config settings such as `config.active_support.report_deprecations`.
These classes are relatively small, however they include lots of
modules as helpers. And if any of the included module hold constants
including it cause the global constant cache to be invalidated
which is really bad for performance.
So when eager loading is enabled we create all the possible classes
as part of the application boot.
Abstract Controller is the common component between Action Mailer and
Action Controller so if we need to share the caching component it need
to be there.
This is a private place to put those AS features that are used
by every component. Nowadays we cherry-pick individual files
wherever they are used, but that it is not worth the effort
for stuff that is going to be loaded for sure sooner or later,
like blank?, autoload, concern, etc.
* A new module (ActiveSupport::Autoload) is provide that extends
autoloading with new behavior.
* All autoloads in modules that have extended ActiveSupport::Autoload
will be eagerly required in threadsafe environments
* Autoloads can optionally leave off the path if the path is the same
as full_constant_name.underscore
* It is possible to specify that a group of autoloads live under an
additional path. For instance, all of ActionDispatch's middlewares
are ActionDispatch::MiddlewareName, but they live under
"action_dispatch/middlewares/middleware_name"
* It is possible to specify that a group of autoloads are all found
at the same path. For instance, a number of exceptions might all
be declared there.
* One consequence of this is that testing-related constants are not
autoloaded. To get the testing helpers for a given component,
require "component_name/test_case". For instance, "action_controller/test_case".
* test_help.rb, which is automatically required by a Rails application's
test helper, requires the test_case.rb for all active components, so
this change will not be disruptive in existing or new applications.
