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UObject Instance Creation

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NewObject

NewObject() is the simplest UObject factory method. It takes in an optional outer object and class and creates a new instance with an automatically generated name.

template< class T >
T* NewObject
(
    UObject* Outer=(UObject*)GetTransientPackage(),
    UClass* Class=T::StaticClass() 
)

Parameter

Description

Outer

Optional. A UObject to set as the Outer for the Object being created.

Class

Optional. A UClass specifying the class of the Object to be created.

Return Value

A pointer to the spawned instance of the specified class.

NewNamedObject

NewNamedObject() expands on NewObject() by allowing a name for the new instance as well as Object Flags and a template object to be specified as an argument.

template< class TClass >
TClass* NewNamedObject
(
    UObject* Outer, 
    FName Name, 
    EObjectFlags Flags = RF_NoFlags, 
    UObject const* Template=NULL
)

Parameter

Description

Outer

A UObject to set as the Outer for the Object being created.

Name

An FName to set as the Name for the new Object.

Flags

Optional. An FObjectFlags enum value describing the new Object.

Template

Optional. A UObject to use as a template when creating the new Object.

Return Value

A pointer to the spawned instance of the specified class.

ConstructObject

For complete flexibility, new instances of UObjects can be created using the ConstructObject() function. This function calls StaticConstructObject(), which allocates the Object, executes the ClassConstructor, and performs any initialization such as loading config properties, loading localized properties, and instancing components.

template< class T >
T* ConstructObject
(
    UClass* Class, 
    UObject* Outer = (UObject*)GetTransientPackage(), 
    FName Name=NAME_None, 
    EObjectFlags SetFlags=RF_NoFlags, 
    UObject const* Template=NULL, 
    bool bCopyTransientsFromClassDefaults=false, 
    struct FObjectInstancingGraph* InstanceGraph=NULL 
)

Parameter

Description

Class

A UClass specifying the class of the Object to be created.

Outer

Optional. A UObject to set as the Outer for the Object being created.

Name

Optional. An FName to set as the Name for the new Object.

SetFlags

Optional. An EObjectFlags enum value describing the new Object.

Template

Optional. A UObject to use as a template when creating the new Object.

bCopyTransientsFromClassDefaults

Optional. A bool that determines whether to copy transient properties from the class default object instead of the passed-in archetype pointer. If true, the class default object's transients are used.

FObjectInstancingGraph

Optional. An FObjectInstancingGraph struct that contains the mappings of instanced objects and components to their templates. Used when for instancing components owned by the new Object.

Return Value

A pointer to the spawned instance of the specified class.

Object Flags

The EObjectFlags enumeration is used to quickly and succinctly describe an Object. There are various flags to describe the type of Object, how it is handled by garbage collection, the stage the Object is at in its lifetime, etc. There are also special all or none masks and predefined groups of flags.

Flag

Value

Description

Object Type

RF_Public

0x00000001

The Object is visible outside of the package it is contained within.

RF_Standalone

0x00000002

The Object is kept around for editing even if is not referenced by anything.

RF_Native

0x00000004

The Objectis native. This is only used for UClass objects.

RF_Transactional

0x00000008

The Object is transactional.

RF_ClassDefaultObject

0x00000010

The Object is the default object for its class, i.e. the default template that new instances of that class use when being created.

RF_ArchetypeObject

0x00000020

The Object is a template for another object. It is treated like a class default object.

RF_Transient

0x00000040

The Object is not saved to disk.

Garbage Collection

RF_RootSet

0x00000080

The Object is not garbage collected even if it is not referenced by anything.

RF_IsLazyReferenced

0x00000100

The Object is referenced by a lazy pointer and requires additional cleanup upon deletion.

RF_Unreachable

0x00000200

The Object is not reachable on the object graph.

RF_TagGarbageTemp

0x00000400

The Object is marked for use by various utilities that use garbage collection. This flag is not interpreted by the garbage collector itself.

Object Lifetime

RF_NeedLoad

0x00000800

The Object needs loading.

RF_AsyncLoading

0x00001000

The Object is being loaded asynchronously.

RF_NeedPostLoad

0x00002000

The Object needs to be post-loaded.

RF_NeedPostLoadSubobjects

0x00004000

The Object still needs to instance sub-objects and fix up serialized component references

RF_PendingKill

0x00008000

The Object is pending destruction. Marks the Object as being invalid for gameplay purposes, but still a valid Object.

RF_BeginDestroyed

0x00010000

The Object has had BeginDestroy() called on it.

RF_FinishDestroyed

0x00020000

The Object has had FinishDestroy() called on it.

Special Masks

RF_AllFlags

0x0003ffff

The Object has all flags. Used mainly for error checking.

RF_NoFlags

0x00000000

The Object has no flags. Used to avoid a cast.

Predefined Groups

RF_Load

RF_Public | RF_Standalone | RF_Native | RF_Transactional | RF_ClassDefaultObject | RF_ArchetypeObject

Flags loaded from Unreal files.

RF_PropagateToSubobjects

RF_Public | RF_ArchetypeObject | RF_Transactional

Flags inherited by sub-objects from their super-objects.