History

History is an internal utility system for undo and redo recording.

Fetch it with Dependency(History) from one of your own systems.

record()

Starts a ChangeHistoryService recording and returns control methods for finishing it.

Type

record(name: string, description?: string): {
	commit(options?: object): void;
	append(options?: object): void;
	cancel(options?: object): void;
}

Notes

• If another recording is still open, comet cancels the older recording, logs a warning, and starts a new one.
• commit() finishes with Enum.FinishRecordingOperation.Commit.
• append() finishes with Enum.FinishRecordingOperation.Append.
• cancel() finishes with Enum.FinishRecordingOperation.Cancel.

Usage

const recording = this.history.record("Create Part");

const part = new Instance("Part");
part.Parent = workspace;

recording.commit();

try()

Wraps record() in a pcall-style flow.

Type

try<T extends Callback>(name: string, fn: T, ...args: Parameters<T>): Promise<ReturnType<T>>
try<T extends Callback>(
	config: {
		name: string;
		description?: string;
		onSuccess?: "commit" | "append" | "cancel";
	},
	fn: T,
	...args: Parameters<T>
): Promise<ReturnType<T>>

Notes

• onSuccess defaults to commit.
• The callback itself is run with pcall. Errors thrown directly in the callback cancel the recording and are rethrown.
• History.try() does not await asynchronous work inside the callback before finishing the recording.

Usage

await this.history.try(
	{
		name: "Duplicate Selection",
		onSuccess: "append",
	},
	() => {
		for (const instance of game.GetService("Selection").Get()) {
			instance.Clone().Parent = instance.Parent;
		}
	},
);

undo()

Calls ChangeHistoryService.Undo().

Type

undo(): void

redo()

Calls ChangeHistoryService.Redo().

Type

redo(): void