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Designing Elixir Systems with OTP

Implementing QuizSession

Let's finish making our second GenServer.

We'll cover the following...

Answering a question

Now, a user can start a quiz with a start_link and a call to :select_question. What remains is to answer a question. We’ll enter them in lib/mastery/boundary/quiz_session.ex:

C++
  def handle_call({:answer_question, answer}, _from, {quiz, email}) do 
    quiz
    |> Quiz.answer_question(Response.new(quiz, email, answer))
    |> Quiz.select_question
    |> maybe_finish(email)
  end
  defp maybe_finish(nil, _email), do: {:stop, :normal, :finished, nil} 
  
  defp maybe_finish(quiz, email) do
    {
      :reply,
      {quiz.current_question.asked, quiz.last_response.correct},
      {quiz, email}
    }
  end

  • This function calls answer_question to answer the question and then advance the quiz.

  • It returns the presentation data that we will need later to show to the user the ...