关于使用枚举作为索引的优化

关于使用枚举作为索引的优化

看了别人的博客学的，记录下，留用！

源代码

enum TemplateCode
{
    None = 0,
    Head = 1,
    Menu = 2,
    Foot = 3,
    Welcome = 4,
}

public string GetHtml(TemplateCode tc)
{
    switch (tc)
    {
        case TemplateCode.Head:
            return GetHead();
        case TemplateCode.Menu:
            return GetMenu();
        case TemplateCode.Foot:
            return GetFoot();
        case TemplateCode.Welcome:
            return GetWelcome();
        default:
            throw new ArgumentOutOfRangeException("tc");
    }
}

优化后

		public enum TemplateCode
        {
            Head = 1,
            Menu = 2,
            Foot = 3,
            Welcome = 4
        }
        public string GetHtml(TemplateCode tc, string msg)
        {
            Func<string, string> func;
            if (TemplateDict.TryGetValue(tc, out func))
            {
                return func(msg);
            }
            return "do nothing";
        }
        public readonly static Dictionary<TemplateCode, Func<string, string>> TemplateDict = InitTemplateFunction();

        private static Dictionary<TemplateCode, Func<string, string>> InitTemplateFunction()
        {
            var ditc = new Dictionary<TemplateCode, Func<string, string>>();
            ditc.Add(TemplateCode.Head, GetHead);
            ditc.Add(TemplateCode.Menu, GetMenu);
            ditc.Add(TemplateCode.Foot, GetFoot);
            ditc.Add(TemplateCode.Welcome, GetWelcome);
            return ditc;
        }
        public static string GetHead(string msg)
        {
            return msg + "a";
        }
        public static string GetMenu(string msg)
        {
            return msg + "b";
        }
        public static string GetFoot(string msg)
        {
            return msg + "c";
        }
        public static string GetWelcome(string msg)
        {
            return msg + "d";
        }

这种优化在分支比较多的时候很好用,少的时候作用有限