1 files changed, 22 insertions, 21 deletions
diff --git a/actionpack/lib/action_view/renderer/partial_renderer.rb b/actionpack/lib/action_view/renderer/partial_renderer.rb
index c0ac332c4e..fc8a6b3107 100644
--- a/actionpack/lib/action_view/renderer/partial_renderer.rb
+++ b/actionpack/lib/action_view/renderer/partial_renderer.rb
@@ -206,13 +206,6 @@ module ActionView
   #     <%- end -%>
   #   <% end %>
   class PartialRenderer < AbstractRenderer #:nodoc:
-    PARTIAL_NAMES = Hash.new {|h,k| h[k] = {} }
-
-    def initialize(*)
-      super
-      @partial_names = PARTIAL_NAMES[@lookup_context.prefixes.first]
-    end
-
     def render(context, options, block)
       setup(context, options, block)
 
@@ -359,28 +352,36 @@ module ActionView
       segments
     end
 
+    PARTIAL_PATHS = {}
+
     def partial_path(object = @object)
-      @partial_names[object.class.name] ||= begin
-        object = object.to_model if object.respond_to?(:to_model)
-        object.class.model_name.partial_path.dup.tap do |partial|
-          path = @lookup_context.prefixes.first
-          merge_path_into_partial(path, partial)
-        end
+      object = object.to_model if object.respond_to?(:to_model)
+
+      path = if object.respond_to?(:to_path)
+               object.to_path
+             else
+               ActiveSupport::Deprecation.warn "ActiveModel-compatible objects whose classes return a #model_name that responds to #partial_path are deprecated. Please respond to #to_path directly instead."
+               object.class.model_name.partial_path
+             end
+
+      prefix = @lookup_context.prefixes.first
+      PARTIAL_PATHS[ [path, prefix] ] ||= path.dup.tap do |object_path|
+        merge_prefix_into_object_path(prefix, object_path)
       end
     end
 
-    def merge_path_into_partial(path, partial)
-      if path.include?(?/) && partial.include?(?/)
+    def merge_prefix_into_object_path(prefix, object_path)
+      if prefix.include?(?/) && object_path.include?(?/)
         overlap = []
-        path_array = File.dirname(path).split('/')
-        partial_array = partial.split('/')[0..-3] # skip model dir & partial
+        prefix_array = File.dirname(prefix).split('/')
+        object_path_array = object_path.split('/')[0..-3] # skip model dir & partial
 
-        path_array.each_with_index do |dir, index|
-          overlap << dir if dir == partial_array[index]
+        prefix_array.each_with_index do |dir, index|
+          overlap << dir if dir == object_path_array[index]
         end
 
-        partial.gsub!(/^#{overlap.join('/')}\//,'')
-        partial.insert(0, "#{File.dirname(path)}/")
+        object_path.gsub!(/^#{overlap.join('/')}\//,'')
+        object_path.insert(0, "#{File.dirname(prefix)}/")
       end
     end