adjust API

app/models/topic_list.rb

@@ -6,11 +6,11 @@ class TopicList
   cattr_accessor :preloaded_custom_fields
   self.preloaded_custom_fields = Set.new
 
-  def self.on_preload(blk)
+  def self.on_preload(&blk)
     (@preload ||= Set.new) << blk
   end
 
-  def self.cancel_preload(blk)
+  def self.cancel_preload(&blk)
     if @preload
       @preload.delete blk
       if @preload.length == 0

spec/models/topic_list_spec.rb

@@ -36,12 +36,12 @@ describe TopicList do
         preloaded_topic = true
       end
 
-      TopicList.on_preload(preloader)
+      TopicList.on_preload(&preloader)
 
       topic_list.topics
       expect(preloaded_topic).to eq(true)
 
-      TopicList.cancel_preload(preloader)
+      TopicList.cancel_preload(&preloader)
     end
   end