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

3 files changed, 29 insertions, 4 deletions

diff --git a/actionpack/CHANGELOG b/actionpack/CHANGELOG
index d8e390c9d4..faf5228dee 100644
--- a/actionpack/CHANGELOG
+++ b/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]
diff --git a/actionpack/lib/action_controller/base.rb b/actionpack/lib/action_controller/base.rb
index 8823076fcc..2125637192 100755
--- a/actionpack/lib/action_controller/base.rb
+++ b/actionpack/lib/action_controller/base.rb
@@ -400,7 +400,6 @@ module ActionController #:nodoc:
       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 @@ module ActionController #:nodoc:
         @assigns  = @response.template.assigns
 
         @headers  = @response.headers
+
+        assign_deprecated_shortcuts(request, response)
       end
 
 
@@ -950,8 +951,15 @@ module ActionController #:nodoc:
 
       # 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 @@ module ActionController #:nodoc:
       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)
diff --git a/actionpack/test/controller/deprecated_instance_variables_test.rb b/actionpack/test/controller/deprecated_instance_variables_test.rb
index 81e7ba1324..edfd8b7d02 100644
--- a/actionpack/test/controller/deprecated_instance_variables_test.rb
+++ b/actionpack/test/controller/deprecated_instance_variables_test.rb
@@ -2,6 +2,15 @@ require File.dirname(__FILE__) + '/../abstract_unit'
 
 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 @@ class DeprecatedInstanceVariablesTest < Test::Unit::TestCase
       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