Macro for defining typed port contracts with defport declarations.

use HexPort.Contract imports the defport macro and registers a @before_compile hook that generates:

• @callback declarations on the contract module itself — the contract module is the behaviour
• __port_operations__/0 — introspection metadata

Contracts are purely static interface definitions. They do not generate a dispatch facade (.Port module) — that is the concern of HexPort.Facade, which the consuming application uses separately to bind a contract to an OTP application's config.

Usage

defmodule MyApp.Todos do
  use HexPort.Contract

  defport get_todo(tenant_id :: String.t(), id :: String.t()) ::
    {:ok, Todo.t()} | {:error, term()}

  defport list_todos(tenant_id :: String.t()) :: [Todo.t()]
end

This generates @callback declarations on MyApp.Todos and MyApp.Todos.__port_operations__/0.

Implementations use @behaviour MyApp.Todos directly:

defmodule MyApp.Todos.Ecto do
  @behaviour MyApp.Todos
  # ...
end

Compatible with Mox.defmock(Mock, for: MyApp.Todos).

To generate a dispatch facade, use HexPort.Facade in a separate module:

defmodule MyApp.Todos do
  use HexPort.Facade, contract: MyApp.Todos.Contract, otp_app: :my_app
end

See HexPort.Facade for dispatch configuration and HexPort for an overview.