FAQ
Answers to the questions that come up most often.
General
What is VeSignal?
VeSignal is a high-performance Luau signal library for Roblox. It provides typed, priority-ordered events with connection pooling, multiple firing modes, and UDTF-derived type signatures that propagate your signal's Signature type to Fire, Wait, and all connect methods.
Does VeSignal require the new Luau type solver?
Only for full type inference. VeSignal works at runtime under the classic solver, but the UDTF type functions (FireSignature, WaitSignature) that derive Fire and Wait signatures require --!strict with the new solver enabled.
Is VeSignal free?
Yes. VeSignal is released under the MIT License.
Can I use VeSignal on both the server and client?
Yes. VeSignal has no RunService dependency. Require it on the server, client, or any shared ModuleScript.
Connections
What's the difference between Connect and ConnectAsync?
Connect calls the listener synchronously on the firing coroutine. ConnectAsync dispatches the listener to a pooled coroutine thread — the firing coroutine continues immediately and the listener runs independently. Use ConnectAsync whenever a listener needs to yield.
What does ConnectIf do differently from guarding inside the callback?
The result is the same for sync connections, but ConnectIf keeps the guard at the call site and makes intent explicit. For ConnectIfAsync, there is an additional benefit: if the predicate fails, no thread is acquired and no resume overhead is paid.
When should I use OnceTimeout over Once?
Use OnceTimeout when the event is expected but not guaranteed within a known window — button presses, server acknowledgements, NPC interactions. If the event never fires, OnceTimeout cleans up the connection automatically so there is no leak.
What happens if OnceTimeout fires and the signal also fires?
The done flag ensures only the first one wins. If the signal fires before the timeout, the callback is called and the timeout fires silently with no effect. If the timeout fires first, the connection is removed and the signal fire is ignored.
What happens to connections when a signal is destroyed?
Destroy calls DisconnectAll, which disconnects every active connection and returns them to the internal pool. If the signal wraps a RBXScriptSignal, the underlying Roblox connection is also disconnected.
Firing
Which Fire variant should I use by default?
Use Fire. It respects each connection's IsAsync flag — sync listeners run directly, async listeners are dispatched to threads. It has a fast path when all listeners are sync (zero thread overhead).
When should I use FireSync?
When you know all listeners are sync and want the lowest possible overhead. FireSync skips all async bookkeeping entirely.
When should I use FireDeferred?
When you want to break re-entrance. If a signal fires while it is already firing, VeSignal defers the second fire via task.defer. FireDeferred always defers — useful when you intentionally want the fire to happen on the next cycle.
When should I use FireSafe?
When listeners are untrusted (user plugins, modular systems) or when you need to guarantee that arguments are not mutated across listeners. FireSafe deep-copies table arguments and wraps each listener in pcall, surfacing errors as warn output.
Combinators
Does Signal.any fire once or every time?
Every time. The combined signal re-fires whenever any input fires. If you only want the first, call Once on the combined signal.
Does Signal.all fire every time after all inputs have fired?
Yes. Once the "all inputs have fired" threshold is crossed, every subsequent fire from any input triggers the combined signal. If you want a one-shot, call Once on the combined signal.
Do I need to destroy combined signals?
Yes, if the combined signal is no longer needed. Its Destroy method disconnects all input connections. If you only call Destroy on the input signals without destroying the combined signal, the internal connections are left dangling.
Priority
What is the default priority?
0. Connections with the same priority fire in insertion order.
Does a higher number mean higher or lower priority?
Higher number = runs first. Use positive integers to front-run default listeners, negative integers to run last.
Performance
Is VeSignal safe to call every frame?
Yes. Fire and Connect/Disconnect are designed for hot paths. Connections are pooled (up to 1000 by default) to avoid allocation on reconnect-heavy code paths. Thread pools are reused across fires.
What is the connection pool?
When a connection is disconnected, VeSignal holds it in an internal pool rather than letting it be garbage collected. The next Connect call reuses a pooled object instead of allocating a new table. The pool cap is 1000 connections.