Sorry, I was saying that your ideal view is the current behavior. For example:

iex(1)> defmodule A do
...(1)>   @enforce_keys [:name]
...(1)>   defstruct [:name, :age]
...(1)> end
{:module, A,
 <<70, 79, 82, 49, 0, 0, 8, 128, 66, 69, 65, 77, 65, 116, 85, 56, 0, 0, 1, 14,
   0, 0, 0, 27, 8, 69, 108, 105, 120, 105, 114, 46, 65, 8, 95, 95, 105, 110,
   102, 111, 95, 95, 9, 102, 117, 110, 99, ...>>, %A{age: nil, name: nil}}
iex> %A{age: 1}
** (ArgumentError) the following keys must also be given when building struct A: [:name]
    expanding struct: A.__struct__/1
    iex:3: (file)

iex> %A{name: nil}
%A{age: nil, name: nil}

Enforce keys doesn’t care about nil values, only keys. Does that clear things up?

Oh I see. So keys listed under enforce_keys must be present in the constructor and that’s all. They are, in a sense, like positional args to functions as they need to be always present.