Protocol for tagging events for grouping.

This protocol is provided for consumers of the event log who want to group events by type. The accumulator itself does not use this protocol - it simply accumulates all events in a list.

Example

alias Skuld.Effects.EventAccumulator.IEvent

# Get events grouped by tag
{result, events} = comp |> EventAccumulator.with_handler(output: &{&1, &2}) |> Comp.run!()
events_by_tag = Enum.group_by(events, &IEvent.tag/1)

Default Behavior

By default (via the Any implementation), structs are tagged by their module name:

IEvent.tag(%MyApp.UserCreated{user_id: 1})
#=> MyApp.UserCreated

Custom Implementation

You can implement the protocol for custom grouping:

defimpl Skuld.Effects.EventAccumulator.IEvent, for: MyApp.DomainEvent do
  def tag(%{aggregate_type: type}), do: type
end