1.ex

    defmodule HelloWeb do
      def controller do
        quote do
          use Phoenix.Controller, namespace: HelloWeb
          import Plug.Conn
          import HelloWeb.Router.Helpers
          import HelloWeb.Gettext
        end
      end

      def view do
        quote do
          use Phoenix.View, root: "lib/hello_web/templates",
                            namespace: HelloWeb

          # Import convenience functions from controllers
          import Phoenix.Controller, only: [get_flash: 2, view_module: 1]

          # Use all HTML functionality (forms, tags, etc)
          use Phoenix.HTML

          import HelloWeb.Router.Helpers
          import HelloWeb.ErrorHelpers
          import HelloWeb.Gettext
        end
      end

      def router do
        quote do
          use Phoenix.Router
          import Plug.Conn
          import Phoenix.Controller
        end
      end

      def channel do
        quote do
          use Phoenix.Channel
          import HelloWeb.Gettext
        end
      end

      defmacro __using__(which) when is_atom(which) do
        apply(__MODULE__, which, [])
      end
    end