defmodule OnePiece.Commanded.ValueObject do
  @moduledoc """
  Defines a module as a "Value Object". For more information about value objects,
  please read the following:

  - [Value Object Wikipedia](https://en.wikipedia.org/wiki/Value_object)
  - [ValueObject by Martin Fowler](https://martinfowler.com/bliki/ValueObject.html)
  """

  @doc """
  Converts the module into an `Ecto.Schema`, and derive from `Jason.Encoder`.

  ## Usage

      defmodule MyValueObject do
        use OnePiece.Commanded.ValueObject

        embedded_schema do
          # ...
        end
      end
  """
  @spec __using__(opts :: []) :: any()
  defmacro __using__(_opts \\ []) do
    quote do
      use Ecto.Schema
      @derive Jason.Encoder
      @primary_key false
    end
  end
end