There’s already a setting for module attributes, which controls if their values are accumulated or replaced.

Even more concretely: Module.register_attribute

defmodule Xyz do
  Module.register_attribute(__MODULE__, :cars, accumulate: true)

  @cars "Toyota"

  def do_stuff(), do: IO.puts("hey there")

  @cars ", "
  @cars "Hyundai"

  def show_cars(), do: IO.puts(@cars)
end

Then in iex:

iex(1)> Xyz.show_cars()
Hyundai, Toyota
:ok

Note that if you put integers they’ll be accumulated in a list. Strings however just get appended at the end of the previous value.

It was for this PR

I assumed it would accumulate, and did a wrong implementation in the first PR: