Unreal Reactive Event

#pragma once

#include "CoreMinimal.h"
#include "UObject/NoExportTypes.h"
#include "ReactiveEvent.generated.h"

DECLARE_DYNAMIC_DELEGATE(FReactiveEventDelegate);
DECLARE_DYNAMIC_MULTICAST_DELEGATE(FReactiveEventDelegateMulti);

UCLASS(Blueprintable, BlueprintType)
    class PROJECTNAME_API UReactiveEvent : public UObject
{
    GENERATED_BODY()
public:
    FReactiveEventDelegateMulti OnEventInvoked;

    bool bWasCalled;


    UFUNCTION(BlueprintCallable)
    void Subscribe(const FReactiveEventDelegate& callback)
    {
        OnEventInvoked.Add(callback);
        if(bWasCalled)
        {
            callback.Execute();
        }
    }

    UFUNCTION(BlueprintCallable)
    void OnNext()
    {
        bWasCalled = true;
        OnEventInvoked.Broadcast();
    }
};