public DeleteHoldOperation(NoteBook book, Hold hold) { Invoke += () => { book.UnPutHold(hold); }; Undo += () => { book.PutHold(hold); }; }
public AddHoldOperation(NoteBook book, Hold hold) { Invoke = () => { book.PutHold(hold); }; Undo = () => { book.UnPutHold(hold); }; }