Getting Started

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SignalBus is a standalone Unreal Engine plugin for typed, local publisher-subscriber messages. It supports World and Game Instance scopes, Immediate and Queued dispatch, C++ and Blueprint use, and optional runtime diagnostics.

First Message

1. Enable SignalBus in the project.
2. Declare a reflected payload USTRUCT.
3. Choose a stable FSignalBusMessageId such as Game.Inventory.CountChanged.
4. Subscribe through USignalBusWorldSubsystem or USignalBusGameInstanceSubsystem.
5. Publish through the same subsystem scope.

USTRUCT()
struct FInventoryCountChanged
{
  GENERATED_BODY()

  UPROPERTY()
  int32 Count = 0;
};

const FSignalBusMessageId MessageId(TEXT("Game.Inventory.CountChanged"));
USignalBusWorldSubsystem* Bus = World->GetSubsystem<USignalBusWorldSubsystem>();
FSignalBusSubscriptionHandle Handle = Bus->Subscribe<FInventoryCountChanged>(
  MessageId,
  Owner,
  FSignalBusMessageCallback::CreateLambda([](const void* Data)
  {
    const FInventoryCountChanged& Payload = *static_cast<const FInventoryCountChanged*>(Data);
  }));

Bus->PublishImmediate(MessageId, FInventoryCountChanged{ 3 }, Owner);

See C++ Usage, Blueprint Usage, and Architecture for scope, lifetime, and delivery details. Use SignalBus Runtime Inspector to observe live activity and SignalBus Runtime Controls to change diagnostic capture settings.