__using__ macro with option

Questions & Help Questions
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2

In case you have a static output like in this example then you can simply call unquote(string) and outside quote block set string variable based on option.

defmodule UsedModule do
  defmacro __using__(opts) do
    string = if opts[:with_extra], do: "with extra", else: "no extra"
    quote do
      def extra(), do: unquote(string)
    end
  end
end

In other case I would recommend to simply move if condition outside quote block and simply use 2 quote calls.

defmodule UsedModule do
  defmacro __using__(opts) do
    if opts[:with_extra] do
      quote do
        def extra(), do: "with extra"
      end
    else
      quote do
        def extra(), do: "no extra"
      end
    end
  end
end

Note: If opts[:with_extra] does not exists then you got nil which is falsy value and therefore we do not need a Keyword.get/3 call here. :smiling_imp: