Building the controller DSL

To successfully call the use Goldcrest.Controller statement, we will need to define a __using__/1 macro in Goldcrest.Controller, which is responsible for injecting a controller-like behavior into a module.

Let’s start by simply moving the Plug.Builder call, the Plug.Conn call, and the call/2 function to the Goldcrest.Controller.__using__/1 macro:

defmodule Goldcrest.Controller do
  import Plug.Conn
  defmacro __using__(_) do
    quote do
      use Plug.Builder
      import Plug.Conn
      def call(conn, action: action) do
        conn = super(conn, [])
        apply(__MODULE__, action, [conn, conn.params])
      end
    end
  end
  # ..
end

In the previous code snippet...