# Define a simple component for containing a "name" value.
defmodule Component.Name do
  defstruct [:value]

  def new(name), do: %__MODULE__{value: name}

  defimpl String.Chars do
    def to_string(%{value: name}), do: name
  end
end

# Define a player entity that will contain components.
defmodule Entity.Player do
  def new(name) do
    ECS.Entity.new([
      Component.Name.new(name)
    ])
  end
end

# Define a system that prints out names of entities that have name components.
defmodule System.DisplayName do
  use ECS.System

  def component_keys, do: [:name]

  def perform(entity) do
    IO.puts entity.name
    entity
  end
end

# Take our modules for a spin!
player = Entity.Player.new("Josh")
ECS.System.run([System.DisplayName], [player])