Define a function at compile-time

Questions & Help Questions
2

These is what module attributes are for: Module — Elixir v1.20.2

I’ve never checked it, but this should work:

  Module.register_attribute(__MODULE__, :rule_ids)

 # Collect the rule ids at compile time
  {_ast, rule_ids_} = File.read!(__ENV__.file)
    |> Code.string_to_quoted()
    |> Macro.traverse([],
      fn
        {:def, _, [{:condition, _, [rule_id, {:v, _, nil}, {:site, _, nil}]} | _]} = x, acc -> {x, [rule_id | acc]}
        other, acc -> {other, acc}
      end,
      fn other, acc -> {other, acc} end
    )
  
  Module.put_attribute(__MODULE__, :rule_ids, rule_ids_)

  # How could I use rule_ids_ here?
  def rule_ids(), do: @rule_ids

  def condition(rule_id, v, site)

  def condition(1018, v, site) do
    v[site][7018] < 50 && v[site][7019] < 50 && v[site][7020] < 50
  end

  def condition(1017, v, site) do
    v[site][7027] > 42
  end

  # ...

end