Class: USystemsSubsystem

class SYSTEMS_API USystemsSubsystem
    : public UGameInstanceSubsystem;

Reflection-enabled

Global accessible registry of systems worlds.

Architecture book page explains more in depth how to interact with systems subsystem, but in a brief: This is a registry of globally accessible systems worlds game can have at any time.

Example

UCLASS()
class EXAMPLE_API UExampleGameInstance : public UGameInstance
{
    GENERATED_BODY()

private:
    virtual void Init() override;
};

void UExampleGameInstance::Init()
{
    Super::Init();

    auto* Subsystem = USystemsSubsystem::Get(GetWorld());
    if (IsValid(Subsystem))
    {
        Subsystem->AcquireSystemsWorld(FName(),
            [&](auto& Systems)
            {
                Systems.RegisterComponent<UShiaComponent>();

                Systems.InstallResource<UShiaSettings>();

                Systems.InstallLambdaSystem(JustDoItSystem, FInstallSystemOptions("JustDoIt"));
            });
    }
}

Methods

  • AcquireSystemsWorld

    public:
void AcquireSystemsWorld(
    FName Id,
    TFunction<SystemSetupFunctor> SetupFunctor
);

    Create, setup and register new systems world.

    Example

    UCLASS()
class EXAMPLE_API AExampleGameMode : public AGameModeBase
{
    GENERATED_BODY()

private:
    virtual void InitGame(const FString& MapName, const FString& Options, FString& ErrorMessage) override;

    virtual void EndPlay(const EEndPlayReason::Type EndPlayReason) override;
};

void AExampleGameMode::InitGame(const FString& MapName, const FString& Options, FString& ErrorMessage)
{
    Super::InitGame(MapName, Options, ErrorMessage);

    auto* Subsystem = USystemsSubsystem::Get(GetWorld());
    if (IsValid(Subsystem))
    {
        Subsystem->AcquireSystemsWorld(FName(),
            [&](auto& Systems)
            {
                Systems.RegisterComponent<UShiaComponent>();

                Systems.InstallResource<UShiaSettings>();

                Systems.InstallLambdaSystem(JustDoItSystem, FInstallSystemOptions("JustDoIt"));
            });
    }
}

void AExampleGameMode::EndPlay(const EEndPlayReason::Type EndPlayReason)
{
    Super::EndPlay(EndPlayReason);

    auto* Subsystem = USystemsSubsystem::Get(GetWorld());
    if (IsValid(Subsystem))
    {
        Subsystem->ReleaseSystemsWorld(ThisClass::SYSTEMS_WORLD);
    }
}

    Arguments

    • Id

      FName Id

      Systems world ID.

    • SetupFunctor

      TFunction<SystemSetupFunctor> SetupFunctor

      Function/lambda that performs setup of created systems world.

      Note

      SystemSetupFunctor has given signature: void(USystemsWorld& Systems).

  • BlueprintAcquireSystemsWorld

    public:
void BlueprintAcquireSystemsWorld(
    FName Id,
    FOnSetupSystemsWorld SetupDelegate
);

    Reflection-enabled

    Specifiers:

    • BlueprintCallable
    • Category = Systems|Subsystem

    Meta Specifiers:

    • DisplayName = Acquire Systems World

    Create, setup and register new systems world.

    Blueprint-side version of USystemsSubsystem::AcquireSystemsWorld.

    Arguments

    • Id

      FName Id

      Systems world ID.

    • SetupDelegate

      FOnSetupSystemsWorld SetupDelegate

      Delegate that performs setup of created systems world.

      Note

      This delegate has given signature: void(USystemsWorld* Systems).

  • Get

    public:
static USystemsSubsystem* Get(
    UWorld* World
);

    Gets instance of this subsystem.

    Arguments

    • World

      UWorld* World

      World context object.

  • GetSystemsWorld

    public:
USystemsWorld* GetSystemsWorld(
    FName Id
);

    Reflection-enabled

    Specifiers:

    • BlueprintCallable
    • Category = Systems|Subsystem

    Meta Specifiers:

    • Displayname = Get Systems World

    Gets systems world by its label.

    Arguments

    • Id

      FName Id

      Systems world ID.

  • GetSystemsWorldsIds

    public:
void GetSystemsWorldsIds(
    TSet<FName>& Output
) const;

    Gets list of all registered systems worlds IDs.

    Useful only for more advanced usecases like editor tools that might want to list currently existing systems world.

    Arguments

  • ReleaseSystemsWorld

    public:
void ReleaseSystemsWorld(
    FName Id
);

    Reflection-enabled

    Specifiers:

    • BlueprintCallable
    • Category = Systems|Subsystem

    Meta Specifiers:

    • Displayname = Release Systems World

    Unregister given systems world.

    Example

    UCLASS()
class EXAMPLE_API AExampleGameMode : public AGameModeBase
{
    GENERATED_BODY()

private:
    virtual void InitGame(const FString& MapName, const FString& Options, FString& ErrorMessage) override;

    virtual void EndPlay(const EEndPlayReason::Type EndPlayReason) override;
};

void AExampleGameMode::InitGame(const FString& MapName, const FString& Options, FString& ErrorMessage)
{
    Super::InitGame(MapName, Options, ErrorMessage);

    auto* Subsystem = USystemsSubsystem::Get(GetWorld());
    if (IsValid(Subsystem))
    {
        Subsystem->AcquireSystemsWorld(FName(),
            [&](auto& Systems)
            {
                Systems.RegisterComponent<UShiaComponent>();

                Systems.InstallResource<UShiaSettings>();

                Systems.InstallLambdaSystem(JustDoItSystem, FInstallSystemOptions("JustDoIt"));
            });
    }
}

void AExampleGameMode::EndPlay(const EEndPlayReason::Type EndPlayReason)
{
    Super::EndPlay(EndPlayReason);

    auto* Subsystem = USystemsSubsystem::Get(GetWorld());
    if (IsValid(Subsystem))
    {
        Subsystem->ReleaseSystemsWorld(ThisClass::SYSTEMS_WORLD);
    }
}

    Arguments

    • Id

      FName Id

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