using System; using System.Collections.Generic; using System.Linq; using System.Web; namespace LanguageFeatures.Models { public static class MyExtensionMethods { public static decimal TotalPrices(this IEnumerable productEnum) { decimal total = 0; foreach (Product prod in productEnum) { total += prod.Price; } return total; } public static IEnumerable FilterByCategory(this IEnumerable productEnum, string categoryParam) { foreach (Product prod in productEnum) { if (prod.Category == categoryParam) { yield return prod; } } } public static IEnumerable Filter(this IEnumerable productEnum, Func selectorParm) { foreach (Product prod in productEnum) { if (selectorParm(prod)) { yield return prod; } } } } }