I'd like to be able to map a domain model to a view model by newing up a view model and passing in the contributing domain model as a parameter (like the code below). My motivation is to keep from re-using mapping code AND to provide a simple way to map (not using automapper yet). A friend says the view model should not know anything about the "payment" domain model that's being passed into the optional constructor. What do you think?

public class LineItemsViewModel
{
    public LineItemsViewModel()
    {
    }

    public LineItemsViewModel(IPayment payment)
    {
        LineItemColumnHeaders = payment.MerchantContext.Profile.UiPreferences.LineItemColumnHeaders;
        LineItems = LineItemDomainToViewModelMapper.MapToViewModel(payment.LineItems);
        ConvenienceFeeAmount = payment.ConvenienceFee.Fee;
        SubTotal = payment.PaymentAmount;
        Total = payment.PaymentAmount + payment.ConvenienceFee.Fee;
    }

    public IEnumerable<Dictionary<int, string>> LineItems { get; set; }
    public Dictionary<int, string> LineItemColumnHeaders { get; set; }
    public decimal SubTotal { get; set; }
    public decimal ConvenienceFeeAmount { get; set; }
    public decimal Total { get; set; }
}