这是ThrowIfNull的另一个实现:

[ThreadStatic]
private static string lastMethodName = null;

[ThreadStatic]
private static int lastParamIndex = 0;

[MethodImpl(MethodImplOptions.NoInlining)]
public static void ThrowIfNull<T>(this T parameter)
{
    var currentStackFrame = new StackFrame(1);
    var props = currentStackFrame.GetMethod().GetParameters();

    if (!String.IsNullOrEmpty(lastMethodName)) {
        if (currentStackFrame.GetMethod().Name != lastMethodName) {
            lastParamIndex = 0;
        } else if (lastParamIndex >= props.Length - 1) {
            lastParamIndex = 0;
        } else {
            lastParamIndex++;
        }
    } else {
        lastParamIndex = 0;
    }

    if (!typeof(T).IsValueType) {
        for (int i = lastParamIndex; i &lt; props.Length; i++) {
            if (props[i].ParameterType.IsValueType) {
                lastParamIndex++;
            } else {
                break;
            }
        }
    }

    if (parameter == null) {
        string paramName = props[lastParamIndex].Name;
        throw new ArgumentNullException(paramName);
    }

    lastMethodName = currentStackFrame.GetMethod().Name;
}

它不像其他实现那样高效，但有更干净的用法:

public void Foo()
{
    Bar(1, 2, "Hello", "World"); //no exception
    Bar(1, 2, "Hello", null); //exception
    Bar(1, 2, null, "World"); //exception
}

public void Bar(int x, int y, string someString1, string someString2)
{
    //will also work with comments removed
    //x.ThrowIfNull();
    //y.ThrowIfNull();
    someString1.ThrowIfNull();
    someString2.ThrowIfNull();

    //Do something incredibly useful here!
}

改变参数为int?也会起作用。

那

用于winforms填充组合框:

List<MyObject> myObjects = new List<MyObject>() { 
    new MyObject() {Name = "a", Id = 0}, 
    new MyObject() {Name = "b", Id = 1}, 
    new MyObject() {Name = "c", Id = 2} }
comboBox.FillDataSource<MyObject>(myObjects, x => x.Name);

扩展方法:

/** <summary>Fills the System.Windows.Forms.ComboBox object DataSource with a 
 * list of T objects.</summary>
 * <param name="values">The list of T objects.</param>
 * <param name="displayedValue">A function to apply to each element to get the 
 * display value.</param>
 */
public static void FillDataSource<T>(this ComboBox comboBox, List<T> values,
    Func<T, String> displayedValue) {

    // Create dataTable
    DataTable data = new DataTable();
    data.Columns.Add("ValueMember", typeof(T));
    data.Columns.Add("DisplayMember");

    for (int i = 0; i < values.Count; i++) {
        // For each value/displayed value

        // Create new row with value & displayed value
        DataRow dr = data.NewRow();
        dr["ValueMember"] = values[i];
        dr["DisplayMember"] = displayedValue(values[i]) ?? "";
        // Add row to the dataTable
        data.Rows.Add(dr);
    }

    // Bind datasource to the comboBox
    comboBox.DataSource = data;
    comboBox.ValueMember = "ValueMember";
    comboBox.DisplayMember = "DisplayMember";
}

内联转换:我喜欢这个小模式。完成了Boolean, Double和DateTime。设计遵循c#的is和作为操作符。

public static Int32? AsInt32(this string s)
{
    Int32 value;
    if (Int32.TryParse(s, out value))
        return value;

    return null;
}

public static bool IsInt32(this string s)
{
    return s.AsInt32().HasValue;
}

public static Int32 ToInt32(this string s)
{
    return Int32.Parse(s);
{

这是一个扩展方法的ASP。Net MVC动作链接助手方法，该方法允许它使用控制器的授权属性来决定该链接是否应该从当前用户视图中启用、禁用或隐藏。 I使您不必在检查所有视图中的用户成员资格的“if”子句中包含受限制的操作。感谢Maarten Balliauw的想法和为我指明道路的代码位。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Security.Principal;
using System.Web.Routing;
using System.Web.Mvc;
using System.Collections;
using System.Reflection;
namespace System.Web.Mvc.Html
{
    public static class HtmlHelperExtensions
    {

        /// <summary>
        /// Shows or hides an action link based on the user's membership status
        /// and the controller's authorize attributes
        /// </summary>
        /// <param name="linkText">The link text.</param>
        /// <param name="action">The controller action name.</param>
        /// <param name="controller">The controller name.</param>
        /// <returns></returns>
        public static string SecurityTrimmedActionLink(
            this HtmlHelper htmlHelper,
            string linkText,
            string action,
            string controller)
        {
            return SecurityTrimmedActionLink(htmlHelper, linkText, action, controller, false, null);
        }

        /// <summary>
        /// Enables, disables or hides an action link based on the user's membership status
        /// and the controller's authorize attributes
        /// </summary>
        /// <param name="linkText">The link text.</param>
        /// <param name="action">The action name.</param>
        /// <param name="controller">The controller name.</param>
        /// <param name="showDisabled">if set to <c>true</c> [show link as disabled - 
        /// using a span tag instead of an anchor tag ].</param>
        /// <param name="disabledAttributeText">Use this to add attributes to the disabled
        /// span tag.</param>
        /// <returns></returns>
        public static string SecurityTrimmedActionLink(
            this HtmlHelper htmlHelper, 
            string linkText, 
            string action, 
            string controller, 
            bool showDisabled, 
            string disabledAttributeText)
        {
            if (IsAccessibleToUser(action, controller, HttpContext.Current ))
            {
                return htmlHelper.ActionLink(linkText, action, controller);
            }
            else
            {
                return showDisabled ? 
                    String.Format(
                        "<span{1}>{0}</span>", 
                        linkText, 
                        disabledAttributeText==null?"":" "+disabledAttributeText
                        ) : "";
            }
        }

        private static IController GetControllerInstance(string controllerName)
        {
            Assembly assembly = Assembly.GetExecutingAssembly();
            Type controllerType = GetControllerType(controllerName);
            return (IController)Activator.CreateInstance(controllerType);
        }

        private static ArrayList GetControllerAttributes(string controllerName, HttpContext context)
        {
            if (context.Cache[controllerName + "_ControllerAttributes"] == null)
            {
                var controller = GetControllerInstance(controllerName);

                context.Cache.Add(
                    controllerName + "_ControllerAttributes",
                    new ArrayList(controller.GetType().GetCustomAttributes(typeof(AuthorizeAttribute), true)),
                    null,
                    Caching.Cache.NoAbsoluteExpiration,
                    Caching.Cache.NoSlidingExpiration,
                    Caching.CacheItemPriority.Default,
                    null);

            }
            return (ArrayList)context.Cache[controllerName + "_ControllerAttributes"];

        }

        private static ArrayList GetMethodAttributes(string controllerName, string actionName, HttpContext context)
        {
            if (context.Cache[controllerName + "_" + actionName + "_ActionAttributes"] == null)
            {
                ArrayList actionAttrs = new ArrayList();
                var controller = GetControllerInstance(controllerName);
                MethodInfo[] methods = controller.GetType().GetMethods();

                foreach (MethodInfo method in methods)
                {
                    object[] attributes = method.GetCustomAttributes(typeof(ActionNameAttribute), true);

                    if ((attributes.Length == 0 && method.Name == actionName)
                        ||
                        (attributes.Length > 0 && ((ActionNameAttribute)attributes[0]).Name == actionName))
                    {
                        actionAttrs.AddRange(method.GetCustomAttributes(typeof(AuthorizeAttribute), true));
                    }
                }

                context.Cache.Add(
                    controllerName + "_" + actionName + "_ActionAttributes",
                    actionAttrs,
                    null,
                    Caching.Cache.NoAbsoluteExpiration,
                    Caching.Cache.NoSlidingExpiration,
                    Caching.CacheItemPriority.Default,
                    null);

            }

            return (ArrayList)context.Cache[controllerName + "_" + actionName+ "_ActionAttributes"]; 
        }

        public static bool IsAccessibleToUser(string actionToAuthorize, string controllerToAuthorize, HttpContext context)
        {
            IPrincipal principal = context.User;

            //cache the attribute list for both controller class and it's methods

            ArrayList controllerAttributes = GetControllerAttributes(controllerToAuthorize, context);

            ArrayList actionAttributes = GetMethodAttributes(controllerToAuthorize, actionToAuthorize, context);                        

            if (controllerAttributes.Count == 0 && actionAttributes.Count == 0)
                return true;

            string roles = "";
            string users = "";
            if (controllerAttributes.Count > 0)
            {
                AuthorizeAttribute attribute = controllerAttributes[0] as AuthorizeAttribute;
                roles += attribute.Roles;
                users += attribute.Users;
            }
            if (actionAttributes.Count > 0)
            {
                AuthorizeAttribute attribute = actionAttributes[0] as AuthorizeAttribute;
                roles += attribute.Roles;
                users += attribute.Users;
            }

            if (string.IsNullOrEmpty(roles) && string.IsNullOrEmpty(users) && principal.Identity.IsAuthenticated)
                return true;

            string[] roleArray = roles.Split(',');
            string[] usersArray = users.Split(',');
            foreach (string role in roleArray)
            {
                if (role == "*" || principal.IsInRole(role))
                    return true;
            }
            foreach (string user in usersArray)
            {
                if (user == "*" && (principal.Identity.Name == user))
                    return true;
            }
            return false;
        }

        private static Type GetControllerType(string controllerName)
        {
            Assembly assembly = Assembly.GetExecutingAssembly();
            foreach (Type type in assembly.GetTypes())
            {
                if (
                    type.BaseType!=null 
                    && type.BaseType.Name == "Controller" 
                    && (type.Name.ToUpper() == (controllerName.ToUpper() + "Controller".ToUpper())))
                {
                    return type;
                }
            }
            return null;
        }

    }
}

在ASP。我总是厌倦了使用FindControl，然后必须强制转换并检查引用之前的值是否为空。所以，我添加了一个TryParse()方法来控制，它反映了框架中类似的Int32等。

public static bool TryParse<T>(this Control control, string id, out T result) 
    where T : Control
{
    result = control.FindControl(id) as T;
    return result != null;
}

现在你可以在ASP中做这个。NET网页表单页面:

Label lbl;
if (Page.TryParse("Label1", out lbl))
{
    lbl.Text = "Safely set text";
}

内置强制转换的FindControl:

public static T FindControl<T>(this Control control, string id) where T : Control
{
    return (T)control.FindControl(id);
}

这没什么了不起的，但我觉得这样可以写出更简洁的代码。

// With extension method
container.FindControl<TextBox>("myTextBox").SelectedValue = "Hello world!";

// Without extension method
((TextBox)container.FindControl("myTextBox")).SelectedValue = "Hello world!";

这可以放在codeplex项目中，如果需要的话