# `DDD.Outbox.DeadLetterPolicy`
[🔗](https://github.com/blackuprise/vicander/blob/v0.1.1/lib/ddd/events/outbox/dead_letter_policy.ex#L1)

Decides what to do with a dead-lettered event.

    defmodule MyApp.DeadLetterPolicy do
      @behaviour DDD.Outbox.DeadLetterPolicy

      @impl true
      def handle(%{event_type: "MyApp.Events.OrderPlaced"}), do: :replay
      def handle(_dead_letter), do: :keep
    end

`handle/1` receives a map with `:id`, `:event_type`, `:aggregate_type`, `:aggregate_id`,
`:payload`, `:attempts`, `:last_error`, `:failed_at` and `:replays`, and returns:

  * `:keep`    - acknowledge it and leave it dead-lettered
  * `:replay`  - make the poller retry it from scratch
  * `:discard` - resolve it as discarded
  * `:later`   - decide on a later sweep (it stays unresolved)

A policy that raises is logged and treated as `:later`, so it can never crash the handler.

# `handle`

```elixir
@callback handle(dead_letter :: map()) :: :keep | :replay | :discard | :later
```

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*Consult [api-reference.md](api-reference.md) for complete listing*