Change the API for setting global options for #url_for to self.url_options = { ... }

	This attr_accessor can be set in a before filter or in the action itself.
    Overwriting default_url_options still works but will output a deprecation notice.

actionpack/lib/action_controller/metal/url_for.rb

@@ -5,7 +5,7 @@ module UrlFor
     include ActionDispatch::Routing::UrlFor
     include ActionController::RackDelegation
 
-    def merge_options(options)
+    def url_options
       super.reverse_merge(
         :host => request.host_with_port,
         :protocol => request.protocol,

actionpack/lib/action_controller/test_case.rb

@@ -336,7 +336,7 @@ def rescue_action_in_public!
     private
       def build_request_uri(action, parameters)
         unless @request.env['REQUEST_URI']
-          options = @controller.__send__(:merge_options, parameters)
+          options = @controller.__send__(:url_options).merge(parameters)
           options.update(:only_path => true, :action => action)
 
           url = ActionController::UrlRewriter.new(@request, parameters)

actionpack/lib/action_dispatch/routing/url_for.rb

@@ -95,22 +95,26 @@ module UrlFor
         self.default_url_options = {}
       end
 
-      def default_url_options(options = nil)
-        self.class.default_url_options
-      end
+      # def default_url_options(options = nil)
+      #   self.class.default_url_options
+      # end
 
       def url_options
-        self.class.default_url_options.merge
+        self.class.default_url_options.merge(@url_options || {})
       end
 
-      def merge_options(options) #:nodoc:
-        if respond_to?(:default_url_options) && (defaults = default_url_options(options))
-          defaults.merge(options)
-        else
-          options
-        end
+      def url_options=(options)
+        @url_options = options
       end
 
+      # def merge_options(options) #:nodoc:
+      #   if respond_to?(:default_url_options) && (defaults = default_url_options(options))
+      #     defaults.merge(options)
+      #   else
+      #     options
+      #   end
+      # end
+
       # Generate a url based on the options provided, default_url_options and the
       # routes defined in routes.rb.  The following options are supported:
       #
@@ -140,7 +144,15 @@ def url_for(options = {})
           when String
             options
           when Hash
-            ActionController::UrlRewriter.rewrite(_router, merge_options(options))
+            # Handle the deprecated instance level default_url_options
+            if respond_to?(:default_url_options, true)
+              ActiveSupport::Deprecation.warn "Overwriting #default_url_options is deprecated. Please set url options with self.url_options = { ... }"
+              if defaults = default_url_options(options)
+                options = defaults.merge(options)
+              end
+            end
+
+            ActionController::UrlRewriter.rewrite(_router, url_options.merge(options))
           else
             polymorphic_url(options)
         end

actionpack/lib/action_dispatch/testing/integration.rb

@@ -357,7 +357,7 @@ def copy_session_variables! #:nodoc:
       extend ActiveSupport::Concern
       include ActionDispatch::Routing::UrlFor
 
-      def merge_options(options)
+      def url_options
         opts = super.reverse_merge(
           :host => host,
           :protocol => https? ? "https" : "http"