让我们把你的优秀和最喜欢的扩展方法列一个列表。
要求是必须发布完整的代码,以及如何使用它的示例和解释。
基于对这个主题的高度兴趣,我在Codeplex上建立了一个名为extensionoverflow的开源项目。
请将您的回答标记为接受,以便将代码放入Codeplex项目。
请张贴完整的源代码,而不是一个链接。
Codeplex上新闻:
24.08.2010 Codeplex页面现在在这里:http://extensionoverflow.codeplex.com/
11.11.2008 XmlSerialize / XmlDeserialize现在是实现和单元测试。
11.11.2008仍有发展空间。;-)现在就加入!
11.11.2008第三位贡献者加入了ExtensionOverflow,欢迎加入BKristensen
11.11.2008 FormatWith现在是实现和单元测试。
09.11.2008第二个贡献者加入ExtensionOverflow。欢迎来到chakrit。
我们需要更多的开发人员。: -)
09.11.2008 ThrowIfArgumentIsNull现已在Codeplex上实现和单元测试。
一些工具IEnumerable: ToString(格式),ToString(函数)和Join(分隔符)。
例如:
var names = new[] { "Wagner", "Francine", "Arthur", "Bernardo" };
names.ToString("Name: {0}\n");
// Name: Wagner
// Name: Francine
// Name: Arthur
// Name: Bernardo
names.ToString(name => name.Length > 6 ? String.Format("{0} ", name) : String.Empty);
// Francine Bernardo
names.Join(" - ");
// Wagner - Francine - Arthur - Bernardo
扩展:
public static string ToString<T>(this IEnumerable<T> self, string format)
{
return self.ToString(i => String.Format(format, i));
}
public static string ToString<T>(this IEnumerable<T> self, Func<T, object> function)
{
var result = new StringBuilder();
foreach (var item in self) result.Append(function(item));
return result.ToString();
}
public static string Join<T>(this IEnumerable<T> self, string separator)
{
return String.Join(separator, values: self.ToArray());
}
下面是一个扩展方法,它适应Rick Strahl的代码(以及注释),使您不必在每次将字节数组或文本文件转换为字符串时猜测或阅读其字节顺序标记。
这个代码片段允许你简单地做:
byte[] buffer = File.ReadAllBytes(@"C:\file.txt");
string content = buffer.GetString();
如果你发现任何错误,请添加到评论中。请随意将它包含在Codeplex项目中。
public static class Extensions
{
/// <summary>
/// Converts a byte array to a string, using its byte order mark to convert it to the right encoding.
/// Original article: http://www.west-wind.com/WebLog/posts/197245.aspx
/// </summary>
/// <param name="buffer">An array of bytes to convert</param>
/// <returns>The byte as a string.</returns>
public static string GetString(this byte[] buffer)
{
if (buffer == null || buffer.Length == 0)
return "";
// Ansi as default
Encoding encoding = Encoding.Default;
/*
EF BB BF UTF-8
FF FE UTF-16 little endian
FE FF UTF-16 big endian
FF FE 00 00 UTF-32, little endian
00 00 FE FF UTF-32, big-endian
*/
if (buffer[0] == 0xef && buffer[1] == 0xbb && buffer[2] == 0xbf)
encoding = Encoding.UTF8;
else if (buffer[0] == 0xfe && buffer[1] == 0xff)
encoding = Encoding.Unicode;
else if (buffer[0] == 0xfe && buffer[1] == 0xff)
encoding = Encoding.BigEndianUnicode; // utf-16be
else if (buffer[0] == 0 && buffer[1] == 0 && buffer[2] == 0xfe && buffer[3] == 0xff)
encoding = Encoding.UTF32;
else if (buffer[0] == 0x2b && buffer[1] == 0x2f && buffer[2] == 0x76)
encoding = Encoding.UTF7;
using (MemoryStream stream = new MemoryStream())
{
stream.Write(buffer, 0, buffer.Length);
stream.Seek(0, SeekOrigin.Begin);
using (StreamReader reader = new StreamReader(stream, encoding))
{
return reader.ReadToEnd();
}
}
}
}
ThrowIfArgumentIsNull是做空检查的好方法,我们都应该这样做。
public static class Extensions
{
public static void ThrowIfArgumentIsNull<T>(this T obj, string parameterName) where T : class
{
if (obj == null) throw new ArgumentNullException(parameterName + " not allowed to be null");
}
}
下面是使用它的方法,它适用于您的命名空间中的所有类或任何您使用该命名空间的地方。
internal class Test
{
public Test(string input1)
{
input1.ThrowIfArgumentIsNull("input1");
}
}
在CodePlex项目上使用这段代码是可以的。
这些扩展方法异步调用事件。他们受到了StackOverflow的启发。
/// <summary>
/// Invoke an event asynchronously. Each subscriber to the event will be invoked on a separate thread.
/// </summary>
/// <param name="someEvent">The event to be invoked asynchronously.</param>
/// <param name="sender">The sender of the event.</param>
/// <param name="args">The args of the event.</param>
/// <typeparam name="TEventArgs">The type of <see cref="EventArgs"/> to be used with the event.</typeparam>
public static void InvokeAsync<TEventArgs>(this EventHandler<TEventArgs> someEvent, object sender, TEventArgs args)
where TEventArgs : EventArgs
{
if (someEvent == null)
{
return;
}
var eventListeners = someEvent.GetInvocationList();
AsyncCallback endAsyncCallback = delegate(IAsyncResult iar)
{
var ar = iar as AsyncResult;
if (ar == null)
{
return;
}
var invokedMethod = ar.AsyncDelegate as EventHandler<TEventArgs>;
if (invokedMethod != null)
{
invokedMethod.EndInvoke(iar);
}
};
foreach (EventHandler<TEventArgs> methodToInvoke in eventListeners)
{
methodToInvoke.BeginInvoke(sender, args, endAsyncCallback, null);
}
}
/// <summary>
/// Invoke an event asynchronously. Each subscriber to the event will be invoked on a separate thread.
/// </summary>
/// <param name="someEvent">The event to be invoked asynchronously.</param>
/// <param name="sender">The sender of the event.</param>
/// <param name="args">The args of the event.</param>
public static void InvokeAsync(this EventHandler someEvent, object sender, EventArgs args)
{
if (someEvent == null)
{
return;
}
var eventListeners = someEvent.GetInvocationList();
AsyncCallback endAsyncCallback = delegate(IAsyncResult iar)
{
var ar = iar as AsyncResult;
if (ar == null)
{
return;
}
var invokedMethod = ar.AsyncDelegate as EventHandler;
if (invokedMethod != null)
{
invokedMethod.EndInvoke(iar);
}
};
foreach (EventHandler methodToInvoke in eventListeners)
{
methodToInvoke.BeginInvoke(sender, args, endAsyncCallback, null);
}
}
使用方法:
public class Foo
{
public event EventHandler<EventArgs> Bar;
public void OnBar()
{
Bar.InvokeAsync(this, EventArgs.Empty);
}
}
请注意,在调用事件之前,您不必检查事件是否为空。例如:
EventHandler<EventArgs> handler = Bar;
if (handler != null)
{
// Invoke the event
}
测试:
void Main()
{
EventHandler<EventArgs> handler1 =
delegate(object sender, EventArgs args)
{
// Simulate performing work in handler1
Thread.Sleep(100);
Console.WriteLine("Handled 1");
};
EventHandler<EventArgs> handler2 =
delegate(object sender, EventArgs args)
{
// Simulate performing work in handler2
Thread.Sleep(50);
Console.WriteLine("Handled 2");
};
EventHandler<EventArgs> handler3 =
delegate(object sender, EventArgs args)
{
// Simulate performing work in handler3
Thread.Sleep(25);
Console.WriteLine("Handled 3");
};
var foo = new Foo();
foo.Bar += handler1;
foo.Bar += handler2;
foo.Bar += handler3;
foo.OnBar();
Console.WriteLine("Start executing important stuff");
// Simulate performing some important stuff here, where we don't want to
// wait around for the event handlers to finish executing
Thread.Sleep(1000);
Console.WriteLine("Finished executing important stuff");
}
调用事件将(通常)产生以下输出:
开始执行重要的事情
处理3
处理2
处理1
完成重要的任务
如果事件是同步调用的,它总是会产生这样的输出-并延迟“重要”内容的执行:
处理1
处理2
处理3
开始执行重要的事情
完成重要的任务