Elixir：如何使用List作为变量定义多个宏？

Question

I'm trying to define two macros with the following code but it failed with ** (CompileError) iex:12: undefined function name/0 . The function parameter name cannot be unquoted in the do block of defmacro .

What is the reason of this ? Is there any way to solve this?

(Elixir version is 1.2.5)

defmodule IEx.MyHelpers do

  def default_env do
    __ENV__
  end

  [:functions, :macros] |> Enum.each(fn name ->
    defmacro unquote(name)(option \\ :all) do
      import MapSet
      quote do
        case unquote(option) do
          x when x in [:a, :all]      -> __ENV__     |> Map.take([unquote(name)])
          x when x in [:d, :default]  -> default_env |> Map.take([unquote(name)])
          x when x in [:i, :imported] ->
            difference(new(Map.take(__ENV__, [unquote(name)])),
                       new(Map.take(default_env, [unquote(name)])))
            |> MapSet.to_list
        end
      end
    end
  end)

end

Answer 1

You basically need to unquote twice, since the dynamic macro generation already is an implicit macro. You should be fine with adding the following line at the top of your defmacro :

name = unquote(name)