using System; namespace CIG { public class Purchase where T : StoreProduct { public Purchase(T product, string transactionID) { this.Product = product; this.TransactionID = transactionID; } public override string ToString() { return string.Concat(new object[] { "[Purchase: TransactionID=", this.TransactionID, ", Product=", this.Product, "]" }); } public T Product { get; private set; } public string TransactionID { get; private set; } } }