[Elixir] add/remove children by unique name under DynamicSupervisor

dynamic_supervisor_children.ex

defmodule DSV do
  use DynamicSupervisor
  
  @registry Registry.ViaTest
  
  def start_link(args), do: DynamicSupervisor.start_link(__MODULE__, args, name: __MODULE__)
  def init(_), do: DynamicSupervisor.init(strategy: :one_for_one)

  def add_child(name) when name |> is_binary do
    pid = child_process(name)
    spec = GS.child_spec(name: pid)
    DynamicSupervisor.start_child(__MODULE__, spec)
  end
  
  def remove_child(name) when name |> is_binary do
    [{pid, _}] = Registry.lookup(@registry, name)
    :ok = DynamicSupervisor.terminate_child(__MODULE__, pid)
    Registry.unregister(Registry.ViaTest, name)
  end
  
  def child_process(name), do: {:via, Registry, {@registry, name}}
end


defmodule GS do
  use GenServer
  
  def start_link(args) do
    opts = args |> Keyword.take([:name])
    GenServer.start_link(__MODULE__, args, opts)
  end
  def init(args), do: {:ok, args}

  def handle_call(:hello, _from, state), do: {:reply, "hello", state}
  def handle_cast(:crash, state), do: raise "Crashed"
end

# Setup
Registry.start_link(keys: :unique, name: Registry.ViaTest)
DSV.start_link([])

# Create child with unique name
name = "todoroki"
DSV.add_child(name)

# communicate!
name |> DSV.child_process |> GenServer.call(:hello)

# crashes and restarts!
name |> DSV.child_process |> GenServer.cast(:term)

# communicate again!
name |> DSV.child_process |> GenServer.call(:hello)

# remove the child
DSV.remove_child(name)

# now you can not talk
name |> DSV.child_process |> GenServer.call(:hello)