08112022 Supervisors - Questions aplenty

[BigSpaces]

Hello @BrooklinJazz,

Several points of mental blocks during the Supervisors exercises.

Question 1: On the Supervised Stack exercise, this is how I first tried to start the supervisor. I don't know what I am doing, really...

children = [%{id: :stack, start: {__MODULE__, :start_link, []}}]
Supervisor.start_link(children, strategy: :one_for_one)

Question 2:
I think I am not grasping the start signature. I do not understand the different parameters or arguments. I feel I am shooting in the dark when creating one. Guidance, please? There are several instances during the exercises in which I fail to grock that first step. Examples:

def start_link(opts) do
    IO.inspect(opts, label: "STARTED DOMINO")
    GenServer.start_link(__MODULE__, opts, name: opts[:name])
  end

Why name: opts[:name] - My brain does not know when we use opts or how

children = [
  %{
    id: :domino1,
    start: {Domino, :start_link, [[name: :domino1]]}
  },
  %{
    id: :domino2,
    start: {Domino, :start_link, [[name: :domino2]]}
  },
  %{
    id: :domino3,
    start: {Domino, :start_link, [[name: :domino3]]}
  }
]

{:ok, supervisor_pid} = Supervisor.start_link(children, strategy: :rest_for_one)

Again I do not understand the start signature [[name: :domino3]]

Question 3:

My implementation of the dying monster does not work... Here is your implementation and mine down below (commented)

 @impl true
  def handle_cast({:attack, damage}, state) do
    new_health = state.health - damage

    if new_health <= 0 do
      raise "dying!"
    else
      {:noreply, %{state | health: new_health}}
    end
  end
   # BrookQuestion - Why is my implementation not working? I don't get it:   

    # case state.health - damage do
    #   0 ->
    #     raise("Morir! Morir!")

    #   true ->
    #     new_state = Map.replace(state, :health, state.health - damage)
    #     {:noreply, new_state}
    # end

Thank you Brook!