Macro does not like module attribute?

Questions & Help Questions
, ,
1

In file 1:

defmodule Utils.Struct do

  # this is for importing definitions when "use Utils.Struct" is called
  defmacro __using__(_opts) do
    quote do
      import Utils.Struct
    end
  end

  defmacro defstruct_module(struct_name, fields) do
    quote do
      defmodule unquote(struct_name) do
        use Utils.Access
        defstruct unquote(fields)
      end
    end
  end

end

In file 2:

defmodule Statistical.Generator do

use Utils.Struct

@in_files [:in_cause, :out_cause, :start]

defstruct_module(State, @in_files)

Breaks:

warning: undefined module attribute @in_files, please remove access to @in_files or explicitly set it before access
  <some file>: Statistical.Generator.State (module)


== Compilation error in file <some file> ==
** (ArgumentError) struct fields definition must be list, got: nil
    (elixir 1.14.4) lib/kernel/utils.ex:117: Kernel.Utils.defstruct/3

But this works - again file 2:

defmodule Statistical.Generator do

use Utils.Struct

@in_files [:in_cause, :out_cause, :start]
in_files = @in_files

defstruct_module(State, in_files)

By the way, if I use the variable approach instead of the module attribute, than the def blocks of the module in file 2 complain… can’t win? :sweat_smile:

Is this because the it inserts the module attribute verbatim as abstract syntax tree? Is there a construct/pattern to handle this case - like would a bind_quote help?

Thank you!