Extract Decorator Step Four

* Promote parameters to instance variables

example_app/app/models/survey.rb

@@ -9,11 +9,8 @@ class Survey < ActiveRecord::Base
 
   def summaries_using(summarizer, options = {})
     questions.map do |question|
-      UnansweredQuestionHider.new.summary_or_hidden_answer(
-        summarizer,
-        question,
-        options[:answered_by]
-      )
+      UnansweredQuestionHider.new(summarizer, options[:answered_by]).
+        summary_or_hidden_answer(question)
     end
   end
 end

example_app/app/models/unanswered_question_hider.rb

@@ -1,11 +1,16 @@
 class UnansweredQuestionHider
   NO_ANSWER = "You haven't answered this question".freeze
 
-  def summary_or_hidden_answer(summarizer, question, user)
-    if hide_unanswered_question?(question, user)
+  def initialize(summarizer, user)
+    @summarizer = summarizer
+    @user = user
+  end
+
+  def summary_or_hidden_answer(question)
+    if hide_unanswered_question?(question)
       hide_answer_to_question(question)
     else
-      question.summary_using(summarizer)
+      question.summary_using(@summarizer)
     end
   end
 
@@ -15,7 +20,7 @@ def hide_answer_to_question(question)
     Summary.new(question.title, NO_ANSWER)
   end
 
-  def hide_unanswered_question?(question, user)
-    user && !question.answered_by?(user)
+  def hide_unanswered_question?(question)
+    @user && !question.answered_by?(@user)
   end
 end

example_app/spec/models/unanswered_question_hider_spec.rb

@@ -5,9 +5,9 @@
     summarizer = stub('summarizer')
     user = build_stubbed(:user)
     question = stub_answered_question(user, false)
-    hider = UnansweredQuestionHider.new
+    hider = UnansweredQuestionHider.new(summarizer, user)
 
-    result = hider.summary_or_hidden_answer(summarizer, question, user)
+    result = hider.summary_or_hidden_answer(question)
 
     result.title.should eq question.title
     result.value.should eq UnansweredQuestionHider::NO_ANSWER
@@ -18,9 +18,9 @@
     user = build_stubbed(:user)
     question = stub_answered_question(user, true)
     summarizer = stub_summarizer(question, summary)
-    hider = UnansweredQuestionHider.new
+    hider = UnansweredQuestionHider.new(summarizer, user)
 
-    result = hider.summary_or_hidden_answer(summarizer, question, user)
+    result = hider.summary_or_hidden_answer(question)
 
     result.should eq summary
   end
@@ -29,9 +29,9 @@
     summary = stub('summary')
     question = build_stubbed(:question)
     summarizer = stub_summarizer(question, summary)
-    hider = UnansweredQuestionHider.new
+    hider = UnansweredQuestionHider.new(summarizer, nil)
 
-    result = hider.summary_or_hidden_answer(summarizer, question, nil)
+    result = hider.summary_or_hidden_answer(question)
 
     result.should eq summary
   end