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FAQ — Frequently Asked Questions

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Do I need to use attributes or source generators

  • No. You can implement IUntargetedMessage<T>, ITargetedMessage<T>, or IBroadcastMessage<T> directly (recommended for structs). Attributes are optional and help tooling/source‑gen.

Which message type should I use?

  • Untargeted - global notifications (any listener).
  • Targeted - commands/events for a specific recipient.
  • Broadcast - facts emitted from a source that others may observe.

How do I enforce ordering?

  • Use the priority parameter at registration; lower runs earlier. Interceptors run before handlers; post‑processors run after.

Can I observe all targets/sources for a type?

  • Yes. Use RegisterTargetedWithoutTargeting<T> or RegisterBroadcastWithoutSource<T> (and their post‑processor counterparts).

How do I diagnose what's happening?

What happens if I register a listener inside a message handler?

  • The newly registered listener will not run for the current message emission. It will only become active starting with the next message emission.
  • This is called "snapshot semantics" — when a message is emitted, DxMessaging takes a snapshot of all current listeners and uses that frozen list for the entire emission.
  • This applies to all listener types (handlers, interceptors, post-processors) and all message categories (Untargeted, Targeted, Broadcast).
  • This behavior prevents infinite loops and ensures predictable execution order. See Interceptors & Ordering for details and examples.

Do I need a global bus?

  • A global bus is provided (MessageHandler.MessageBus). You can also create and pass your own MessageBus instance to isolate subsystems and tests.

Is this compatible with Unity's SendMessage/UnityEvents

  • Yes. You can integrate with legacy patterns via ReflexiveMessage. Prefer DxMessaging for new code.