Unreal Engine 4.26 Documentation

Unreal Engine 4.27 Documentation

Unreal Engine 5.0 Documentation

> Unreal Engine API Reference > Runtime > Core > Misc > FChange

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FChange

[FChange](API\Runtime\Core\Misc\FChange) modifies a [UObject](API\Runtime\CoreUObject\UObject\UObject) and is meant to be used to implement undo/redo.

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Inheritance Hierarchy

FChange

FCommandChange

FToolCommandChange

FActivateToolChange

FAttributeEditor_AttributeListsChange

FBeginGroomCardsEditChange

FBeginToolChange

FComponentWorldTransformChange

FCurveControlPointsMechanicInsertionChange

FCurveControlPointsMechanicModeChange

FCurveControlPointsMechanicMovementChange

FCurveControlPointsMechanicSelectionChange

FDrawPolygonStateChange

FDrawPolyPathStateChange

FEditGroomCardsTopologyPostEditChange

FEditGroomCardsTopologyPreEditChange

FEditMeshMaterials_MaterialSetChange

FEditMeshPolygonsToolMeshChange

FEndGroomCardsEditChange

FGroupEdgeInsertionFirstPointChange

FLatticeControlPointsMechanicMovementChange

FLatticeControlPointsMechanicSelectionChange

FLatticeDeformerToolConstrainedPointsChange

FMeshChange

FMeshPolygroupChange

FMeshReplacementChange

FMeshSelectionChange

FMeshSkinWeightsChange

FMeshVertexChange

FPersistentMeshSelectionChange

FPolyEditActivityStartChange

FPolyEditCutFacesActivityFirstPointChange

FPolygonSelectionMechanicSelectionChange

FSpaceCurveDeformationMechanicMovementChange

FSpaceCurveDeformationMechanicSelectionChange

FToolChangeWrapperChange

FToolCommandChangeSequence

FTransformProxyChange

TIndexedValuesChange

TCustomIndexedValuesChange

FMeshAttributePaintChange

TSimpleValueLambdaChange

TWrappedToolCommandChange

TDataprepBindingCommandChange

FSwapChange

FCompoundChange

References

Module	Core
Header	/Engine/Source/Runtime/Core/Public/Misc/Change.h
Include	#include "Misc/Change.h"

Syntax

class FChange

Remarks

FChange modifies a UObject and is meant to be used to implement undo/redo. The change is embedded in an FTransaction which executes it instead of the standard serialization transaction (cannot be combined - see FTransaction).

The original FChange style (used by MeshEditor) was that calling Execute() would return a new FChange that applies the opposite action, and FTransaction would swap the two at each undo/redo step (eg a "DeleteObject" FChange would return a "CreateObject" FChange)

The alternative "Command Pattern"-style FChange calls Apply() and Revert() on a single FChange.

FChange may eventually be deprecated. You should subclass FSwapChange and FCommandChange to implement these different styles.

Constructors

	Name	Description
	FChange()	Protected default constructor

Destructors

	Name	Description
	~FChange()	Virtual destructor

Functions

	Name	Description
void	Apply ( UObject* Object )	Makes the change to the object
TUniquePtr< ...	Execute ( UObject* Object )	Makes the change to the object, returning a new change that can be used to perfectly roll back this change
EChangeStyle	GetChangeType()	What style of change is this
bool	HasExpired ( UObject* Object )
void	PrintToLog ( FFeedbackContext& FeedbackContext, const int32 IndentLevel )	Prints this change to the log, including sub-changes if there are any.
void	Revert ( UObject* Object )	Reverts change to the object
FString	ToString()	Describes this change (for debugging)

Enums

	Name	Description
	EChangeStyle