global variable

worker.ex

defmodule Dresser.Worker do
  @moduledoc "The store, based on `Agent`."

  def start_link do
    result = Agent.start_link(fn -> %{} end, name: __MODULE__)
    __MODULE__.put(:free_dress, 3)

    result
  end

  @doc "Gets a value"
  @spec get(String.t) :: any
  def get(key) do
    Agent.get(__MODULE__, &Map.get(&1, key))
  end

  @doc "Puts a value"
  @spec put(String.t, any) :: any
  def put(key, value) do
    Agent.update(__MODULE__, &Map.put(&1, key, value))
  end
end