UE5: Using the ThisClass typedef for more concise code

In the Unreal Engine, the Super typedef for a UCLASS’s base class is well known. Less well known is the ThisClass typedef that aliases the derived class itself. Each UCLASS generates its own ThisClass, so it will always refer to the class being defined. It’s useful for saving time when binding delegates or copying code between multiple UCLASSs e.g.

MyCollisionBox->OnComponentBeginOverlap.AddDynamic(
    this,
    &AMyExtremelyVerboseActorTypeName::OnOverlapBegin);
MyCollisionBox->OnComponentBeginOverlap.AddDynamic(
    this,
    &ThisClass::OnOverlapBegin);

I will illustrate the typedef’s source with the following UCLASS definition.

#pragma once

#include "CoreMinimal.h"

#include "ExampleClass.generated.h"

UCLASS()
class UExampleClass : public UObject {
    GENERATED_BODY()
  public:
    UExampleClass();
};

In the expanded GENERATED_BODY macro, we find the typedef.

typedef UObject Super;
typedef UExampleClass ThisClass;

For completeness, we can verify that ThisClass and UExampleClass are the same with static_assert and std::is_same_v from <type_traits>.

#include "ExampleClass.h"

#include <type_traits>

UExampleClass::UExampleClass() {
    static_assert(std::is_same_v<UExampleClass, ThisClass>);
}

ThisClass is a small but useful typedef that can save you time and make your code more concise.