gistfile1.ex

defmodule Check do
  require Lager
  use Phoenix.Controller
  def authed?(conn,f) do
 	try do
 		user = get_user_for_request(conn)
 		token = get_token_for_request(conn)
 		if (token != "xxx1xxx") do
 			Lager.error "bad token error"
 			raise "bad Token"
 		else
 			f.(conn)
 		end
 	rescue	
 		error ->
 			Lager.info "authed? raised error #{inspect error}"
 			text conn, 401, "Unauthorized"
 	end 
  end
  def get_user_for_request(conn) do
  	#todo lookup user from header
 	:foo 
  end
  def get_token_for_request(conn) do
  	#todo put this in the header
 	token = conn.params["token"] 
 	case token do
 		nil -> raise "No Token"
 		token -> token	
 	end
 	Lager.info "checking token #{inspect token}"
 	token
  end
  
end

gistfile2.ex

defmodule Cntrl do
  use Phoenix.Controller
  require Lager
  def do_something(conn) do
    f = fn(conn) ->
      #do some stuff
      text conn, "win"
    end
    Check.authed?(conn,f)
  end
end