Deprecation: check whether instance variables have been monkeyed with before assigning them to deprecation proxies. Raises a RuntimeError if so.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@4717 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

actionpack/CHANGELOG

@@ -1,5 +1,7 @@
 *SVN*
 
+* Deprecation: check whether instance variables have been monkeyed with before assigning them to deprecation proxies. Raises a RuntimeError if so. [Jeremy Kemper]
+
 * Add support for the param_name parameter to the auto_complete_field helper. #5026 [david.a.williams@gmail.com]
 
 * Deprecation! @params, @session, @flash will be removed after 1.2. Use the corresponding instance methods instead. You'll get printed warnings during tests and logged warnings in dev mode when you access either instance variable directly. [Jeremy Kemper]

actionpack/lib/action_controller/base.rb

@@ -400,7 +400,6 @@ def filter_parameter_logging(*filter_words, &block)
       def process(request, response, method = :perform_action, *arguments) #:nodoc:
         initialize_template_class(response)
         assign_shortcuts(request, response)
-        assign_deprecated_shortcuts(request, response)
         initialize_current_url
         assign_names
         forget_variables_added_to_assigns
@@ -942,6 +941,8 @@ def assign_shortcuts(request, response)
         @assigns  = @response.template.assigns
 
         @headers  = @response.headers
+
+        assign_deprecated_shortcuts(request, response)
       end
 
 
@@ -950,8 +951,15 @@ def assign_shortcuts(request, response)
 
       # Gone after 1.2.
       def assign_deprecated_shortcuts(request, response)
-        DEPRECATED_INSTANCE_VARIABLES.each do |var|
-          instance_variable_set "@#{var}", ActiveSupport::Deprecation::DeprecatedInstanceVariableProxy.new(self, var)
+        DEPRECATED_INSTANCE_VARIABLES.each do |method|
+          var = "@#{method}"
+          if instance_variables.include?(var)
+            value = instance_variable_get(var)
+            unless ActiveSupport::Deprecation::DeprecatedInstanceVariableProxy === value
+              raise "Deprecating #{var}, but it's already set to #{value.inspect}! Use the #{method}= writer method instead of setting #{var} directly."
+            end
+          end
+          instance_variable_set var, ActiveSupport::Deprecation::DeprecatedInstanceVariableProxy.new(self, method)
         end
       end
 
@@ -1011,7 +1019,7 @@ def reset_variables_added_to_assigns
       end
 
       def add_instance_variables_to_assigns
-        @@protected_variables_cache ||= protected_instance_variables.inject({}) { |h, k| h[k] = true; h }
+        @@protected_variables_cache ||= Set.new(protected_instance_variables)
         instance_variables.each do |var|
           next if @@protected_variables_cache.include?(var)
           @assigns[var[1..-1]] = instance_variable_get(var)

actionpack/test/controller/deprecated_instance_variables_test.rb

@@ -2,6 +2,15 @@
 
 class DeprecatedInstanceVariablesTest < Test::Unit::TestCase
   class Target < ActionController::Base
+    def initialize(run = nil)
+      instance_eval(run) if run
+      super()
+    end
+
+    def noop
+      render :nothing => true
+    end
+
     ActionController::Base::DEPRECATED_INSTANCE_VARIABLES.each do |var|
       class_eval "def old_#{var}; render :text => @#{var}.inspect end"
       class_eval "def new_#{var}; render :text => #{var}.inspect end"
@@ -28,6 +37,12 @@ def test_new_#{var}_isnt_deprecated
       def test_internal_#{var}_isnt_deprecated
         assert_not_deprecated { get :internal_#{var} }
       end
+      def test_#{var}_raises_if_already_set
+        assert_raise(RuntimeError) do
+          @controller = Target.new '@#{var} = Object.new'
+          get :noop
+        end
+      end
     end_eval
   end
 end