NotNull.h File Reference

#include "CoreTypes.h"
#include "Misc/IntrusiveUnsetOptionalState.h"
#include "Misc/UEOps.h"
#include "Templates/Requires.h"
#include "Templates/TypeHash.h"
#include "Traits/IsImplicitlyConstructible.h"
#include <type_traits>

Go to the source code of this file.

Macros
#define	UE_ENABLE_NOTNULL_WRAPPER   (UE_BUILD_DEBUG || UE_BUILD_DEVELOPMENT)
#define	UE_NOTNULL_FUNCTION_NON_NULL_RETURN_START   FUNCTION_NON_NULL_RETURN_START
#define	UE_NOTNULL_FUNCTION_NON_NULL_RETURN_END   FUNCTION_NON_NULL_RETURN_END

Typedefs
template<typename T >
using	TNotNull = T

Functions
template<typename T >
T &&	NotNullGet (T &&NotNull)

Macro Definition Documentation

UE_ENABLE_NOTNULL_WRAPPER

#define UE_ENABLE_NOTNULL_WRAPPER   (UE_BUILD_DEBUG || UE_BUILD_DEVELOPMENT)

TNotNull is a wrapper template which is used to indicate that a pointer or handle is never intended to be null.

Design and rationale:

• No default construction, construction with nullptr or comparison against nullptr. Attempting to do so will cause a compile error.
• While intended for pointer types, it should be usable for anything else that is nullable, e.g. TFunction.
• The pointer value is checked on construction or assignment, and then never after that. The only exception to this is a TNotNull in a moved-from state, which will not re-check the value. - see below.
• TNotNull is movable. This allows things like TNotNull<TUniquePtr<T>> to be expressed, but means that a moved-from TNotNull variable can end up being null. However, users are never required to handle a variable in this state. If a variable is to be reused after it has been moved from (e.g. a data member of an object that isn't being destroyed) then code that made it null should assign a new non-null value to it before returning to user code or using it to construct or assign to another TNotNull. Users of your variable should never be allowed to see a null value. Compilers and static analyzers are allowed to assume that the pointer is not null and optimize and analyze accordingly.
• The UE_ENABLE_NOTNULL_WRAPPER can be used to disable all checking and become an alias to the inner type, so there is no runtime overhead at all.

UE_NOTNULL_FUNCTION_NON_NULL_RETURN_END

#define UE_NOTNULL_FUNCTION_NON_NULL_RETURN_END   FUNCTION_NON_NULL_RETURN_END

UE_NOTNULL_FUNCTION_NON_NULL_RETURN_START

#define UE_NOTNULL_FUNCTION_NON_NULL_RETURN_START   FUNCTION_NON_NULL_RETURN_START

Typedef Documentation

TNotNull

template<typename T >

using TNotNull = T

Function Documentation

NotNullGet()

template<typename T >

T && NotNullGet

(

T &&

NotNull

)