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。
// Values ordered true/false
// True/false values separated by a capital letter
// Only two values allowed
// ---------------------------
// Limited, but could be useful
public enum BooleanFormat
{
OneZero,
YN,
YesNo,
TF,
TrueFalse,
PassFail,
YepNope
}
public static class BooleanExtension
{
/// <summary>
/// Converts the boolean value of this instance to the specified string value.
/// </summary>
private static string ToString(this bool value, string passValue, string failValue)
{
return value ? passValue : failValue;
}
/// <summary>
/// Converts the boolean value of this instance to a string.
/// </summary>
/// <param name="booleanFormat">A BooleanFormat value.
/// Example: BooleanFormat.PassFail would return "Pass" if true and "Fail" if false.</param>
/// <returns>Boolean formatted string</returns>
public static string ToString(this bool value, BooleanFormat booleanFormat)
{
string booleanFormatString = Enum.GetName(booleanFormat.GetType(), booleanFormat);
return ParseBooleanString(value, booleanFormatString);
}
// Parses boolean format strings, not optimized
private static string ParseBooleanString(bool value, string booleanFormatString)
{
StringBuilder trueString = new StringBuilder();
StringBuilder falseString = new StringBuilder();
int charCount = booleanFormatString.Length;
bool isTrueString = true;
for (int i = 0; i != charCount; i++)
{
if (char.IsUpper(booleanFormatString[i]) && i != 0)
isTrueString = false;
if (isTrueString)
trueString.Append(booleanFormatString[i]);
else
falseString.Append(booleanFormatString[i]);
}
return (value == true ? trueString.ToString() : falseString.ToString());
}
如果有Unix时间戳和ISO 8601格式的日期和时间就太好了。大量用于网站和休息服务。
我在我的Facebook图书馆里使用它。你可以找到源代码http://github.com/prabirshrestha/FacebookSharp/blob/master/src/FacebookSharp.Core/FacebookUtils/DateUtils.cs
private static readonly DateTime EPOCH = DateTime.SpecifyKind(new DateTime(1970, 1, 1, 0, 0, 0, 0),DateTimeKind.Utc);
public static DateTime FromUnixTimestamp(long timestamp)
{
return EPOCH.AddSeconds(timestamp);
}
public static long ToUnixTimestamp(DateTime date)
{
TimeSpan diff = date.ToUniversalTime() - EPOCH;
return (long)diff.TotalSeconds;
}
public static DateTime FromIso8601FormattedDateTime(string iso8601DateTime){
return DateTime.ParseExact(iso8601DateTime, "o", System.Globalization.CultureInfo.InvariantCulture);
}
public static string ToIso8601FormattedDateTime(DateTime dateTime)
{
return dateTime.ToString("o");
}
请随意在codeplex项目中使用。
这是另一双我觉得用不完的鞋:
public static T ObjectWithMin<T, TResult>(this IEnumerable<T> sequence, Func<T, TResult> predicate)
where T : class
where TResult : IComparable
{
if (!sequence.Any()) return null;
//get the first object with its predicate value
var seed = sequence.Select(x => new {Object = x, Value = predicate(x)}).FirstOrDefault();
//compare against all others, replacing the accumulator with the lesser value
//tie goes to first object found
return
sequence.Select(x => new {Object = x, Value = predicate(x)})
.Aggregate(seed,(acc, x) => acc.Value.CompareTo(x.Value) <= 0 ? acc : x).Object;
}
public static T ObjectWithMax<T, TResult>(this IEnumerable<T> sequence, Func<T, TResult> predicate)
where T : class
where TResult : IComparable
{
if (!sequence.Any()) return null;
//get the first object with its predicate value
var seed = sequence.Select(x => new {Object = x, Value = predicate(x)}).FirstOrDefault();
//compare against all others, replacing the accumulator with the greater value
//tie goes to last object found
return
sequence.Select(x => new {Object = x, Value = predicate(x)})
.Aggregate(seed, (acc, x) => acc.Value.CompareTo(x.Value) > 0 ? acc : x).Object;
}
用法:
var myObject = myList.ObjectWithMin(x=>x.PropA);
这些方法基本上取代了像
var myObject = myList.OrderBy(x=>x.PropA).FirstOrDefault(); //O(nlog(n)) and unstable
and
var myObject = myList.Where(x=>x.PropA == myList.Min(x=>x.PropA)).FirstOrDefault(); //O(N^2) but stable
and
var minValue = myList.Min(x=>x.PropA);
var myObject = myList.Where(x=>x.PropA == minValue).FirstOrDefault(); //not a one-liner, and though linear and stable it's slower (evaluates the enumerable twice)
到目前为止,我刚刚浏览了所有4页,我很惊讶,我没有看到这种方式来缩短检查InvokeRequired:
using System;
using System.Windows.Forms;
/// <summary>
/// Extension methods acting on Control objects.
/// </summary>
internal static class ControlExtensionMethods
{
/// <summary>
/// Invokes the given action on the given control's UI thread, if invocation is needed.
/// </summary>
/// <param name="control">Control on whose UI thread to possibly invoke.</param>
/// <param name="action">Action to be invoked on the given control.</param>
public static void MaybeInvoke(this Control control, Action action)
{
if (control != null && control.InvokeRequired)
{
control.Invoke(action);
}
else
{
action();
}
}
/// <summary>
/// Maybe Invoke a Func that returns a value.
/// </summary>
/// <typeparam name="T">Return type of func.</typeparam>
/// <param name="control">Control on which to maybe invoke.</param>
/// <param name="func">Function returning a value, to invoke.</param>
/// <returns>The result of the call to func.</returns>
public static T MaybeInvoke<T>(this Control control, Func<T> func)
{
if (control != null && control.InvokeRequired)
{
return (T)(control.Invoke(func));
}
else
{
return func();
}
}
}
用法:
myForm.MaybeInvoke(() => this.Text = "Hello world");
// Sometimes the control might be null, but that's okay.
var dialogResult = this.Parent.MaybeInvoke(() => MessageBox.Show(this, "Yes or no?", "Choice", MessageBoxButtons.YesNo));