private void addObjectReferenceToList(IFormula formula, IDictionary <string, int> list, IObjectReference objectReference) { var alias = Regex.Replace(objectReference.Alias, @"\s", "_"); try { list.Add(alias, idFor(objectReference.Object)); } catch (ArgumentException ex) { throw new ArgumentException(Error.AliasAlreadyUsedInFormula(alias, formula.ToString()), ex); } }