That’s part of being more idiomatic too, see for example the official advice about not using config for libraries but instead passing options as function arguments. I think this code suggests a middle ground approach (so you could pass it as a function argument in any case, and redefine the default in your module if you’ve dumped the source:
defmodule CodeGenTemplate do
@c1 1
def f1(x, c1 \\ @c1) do
x + c1
end
end
