* 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.
* request.formats is much simpler now
* For XHRs or Accept headers with a single item, we use the Accept header
* For other requests, we use params[:format] or fallback to HTML
* This is primarily to work around the fact that browsers provide completely
broken Accept headers, so we have to whitelist the few cases we can
specifically isolate and treat other requests as coming from the browser
* For APIs, we can support single-item Accept headers, which disambiguates
from the browsers
* Requests to an action that only has an XML template from the browser will
no longer find the template. This worked previously because most browsers
provide a catch-all */*, but this was mostly accidental behavior. If you
want to serve XML, either use the :xml format in links, or explicitly
specify the XML template: render "template.xml".
