Question 1

How to safely unsubscribe from events in NX Horizon without causing errors?

Accepted Answer

Use UnsubscribeAsync when unsubscribing from a synchronous event handler to avoid modifying the subscription collection during iteration. For asynchronous handlers, Unsubscribe is safe, but UnsubscribeAsync is recommended if dispatching mode isn't guaranteed.

Question 2

Can NX Horizon handle cross-thread communication in Delphi GUI apps?

Accepted Answer

Yes, it supports MainSync and MainAsync delivery options to synchronize events with the main thread, making it suitable for GUI applications where UI updates must occur on the main thread.

Question 3

NX Horizon vs Spring4D event bus: which should I choose for Delphi?

Accepted Answer

NX Horizon is more lightweight and focused on thread safety with simple API, while Spring4D offers broader framework integration and features like dependency injection. Choose NX Horizon for pure event bus needs with minimal overhead.

Question 4

How to manage long-running tasks in NX Horizon event handlers to avoid blocking?

Accepted Answer

Use synchronous dispatching (Sync or MainSync) for short handlers, and within the handler, start a TTask.Run on a dedicated thread pool for long-running code, as suggested in the README's dedicated thread pool section.

Question 5

What happens if I forget to call WaitFor in a subscriber destructor?

Accepted Answer

You risk accessing destroyed subscriber instances from already-dispatched event handlers, leading to access violations or undefined behavior. Always call WaitFor before unsubscribing in destructors.

Question 6

How to create separate event channels or observer patterns with NX Horizon?

Accepted Answer

Create multiple TNxHorizon instances or use INxHorizon wrappers for separate channels. For observer patterns, subjects can expose INxHorizon references for observers to subscribe and unsubscribe safely.

Question 7

Is NX Horizon compatible with older Delphi versions like XE4?

Accepted Answer

Yes, it's tested on XE4 and later versions using the classic compiler, and it's platform-agnostic, but asynchronous features rely on PPL available from XE7 onward, which may limit functionality in older versions.

NX-Horizon

What is NX-Horizon?

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Frequently Asked Questions