I would avoid going this path, as the benefit you gain (1 line of code vs 3 lines of code) is not worth it, because it will make the code much less readable.

Actually I would avoid using here __using__ as it is not necessary. I would something like this:

defmodule Attributes do
  defmacro generic_attributes() do
    quote do
      attr :class, :string, default: ""
      attr :id, :string, default: nil
      attr :rest, :global 
    end
  end
end

And using it inside of components by:

require Attributes

Attributes.generic_attributes()

The advantages are:

1. Much more readability, as you can document the macro and have a clear understanding where you use it, opposed to use;
2. Macro defined in this way can only inject code, to avoid people coming later and adding their “smart” ideas.

You are not wrong but I would be completely okay if one module’s only job was to inject code in others. Having huge modules doing many things with many code-injection macros is not exactly a win for readability and maintainability.

In the end it’s your call, and the difference can be easily handled.