# USDLayer.ListOperation A non-destructive list of incremental editing operations for list-valued metadata and properties. ``` struct ListOperation where T : USDLayer._ListOperationElement ``` ## Topics ### Initializers [`init(explicitItems: [T])`](/documentation/USDKit/USDLayer/ListOperation/init(explicitItems:)-4klr9) Creates an explicit-mode list operation with the given items. [`init(explicitItems: [Int])`](/documentation/USDKit/USDLayer/ListOperation/init(explicitItems:)-6l0al) [`init(explicitItems: [UInt])`](/documentation/USDKit/USDLayer/ListOperation/init(explicitItems:)-7iesv) [`init(prependedItems: [T], appendedItems: [T], deletedItems: [T])`](/documentation/USDKit/USDLayer/ListOperation/init(prependedItems:appendedItems:deletedItems:)-1tkyo) Creates a list operation with the given prepended/appended/deleted items. Pass no arguments for an empty operation with no slots authored. [`init(prependedItems: [Int], appendedItems: [Int], deletedItems: [Int])`](/documentation/USDKit/USDLayer/ListOperation/init(prependedItems:appendedItems:deletedItems:)-8poys) [`init(prependedItems: [UInt], appendedItems: [UInt], deletedItems: [UInt])`](/documentation/USDKit/USDLayer/ListOperation/init(prependedItems:appendedItems:deletedItems:)-ngyh) ### Instance Properties [`var appliedItems: [T]`](/documentation/USDKit/USDLayer/ListOperation/appliedItems) The composed result of applying all operations from strongest to weakest opinion. [`var hasKeys: Bool`](/documentation/USDKit/USDLayer/ListOperation/hasKeys) Whether any operation slot has been authored. [`var isExplicit: Bool`](/documentation/USDKit/USDLayer/ListOperation/isExplicit) Whether the operation is in explicit mode — i.e., its items replace the entire list during composition. ### Instance Methods [`func clear()`](/documentation/USDKit/USDLayer/ListOperation/clear()) Removes all authored slots, leaving an empty operation. [`func clearAndMakeExplicit()`](/documentation/USDKit/USDLayer/ListOperation/clearAndMakeExplicit()) Removes all authored slots and switches to explicit mode with no items. [`func compose(stronger: USDLayer.ListOperation, for: USDLayer.ListOperationType)`](/documentation/USDKit/USDLayer/ListOperation/compose(stronger:for:)) Composes a stronger operation into this one for the given slot. [`func has(item: T) -> Bool`](/documentation/USDKit/USDLayer/ListOperation/has(item:)) Returns a Boolean value that indicates whether `item` appears in any slot of this operation. [`func items(for: USDLayer.ListOperationType) -> [T]`](/documentation/USDKit/USDLayer/ListOperation/items(for:)) Returns the items in the given operation’s slot. [`func replaceItems(in: USDLayer.ListOperationType, at: Int, count: Int, with: [T]) throws`](/documentation/USDKit/USDLayer/ListOperation/replaceItems(in:at:count:with:)) Replaces `count` items in `operation`’s slot starting at `index` with `newItems`. [`func setItems([T], for: USDLayer.ListOperationType) throws`](/documentation/USDKit/USDLayer/ListOperation/setItems(_:for:)) Sets the items in the given operation’s slot. ## Relationships ### Conforms To [`USDValueProtocol`](/documentation/USDKit/USDValueProtocol) [`Sendable`](/documentation/Swift/Sendable) [`SendableMetatype`](/documentation/Swift/SendableMetatype) [`Copyable`](/documentation/Swift/Copyable) [`Escapable`](/documentation/Swift/Escapable) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)