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。
对于Winform控件:
/// <summary>
/// Returns whether the function is being executed during design time in Visual Studio.
/// </summary>
public static bool IsDesignTime(this Control control)
{
if (LicenseManager.UsageMode == LicenseUsageMode.Designtime)
{
return true;
}
if (control.Site != null && control.Site.DesignMode)
{
return true;
}
var parent = control.Parent;
while (parent != null)
{
if (parent.Site != null && parent.Site.DesignMode)
{
return true;
}
parent = parent.Parent;
}
return false;
}
/// <summary>
/// Sets the DropDownWidth to ensure that no item's text is cut off.
/// </summary>
public static void SetDropDownWidth(this ComboBox comboBox)
{
var g = comboBox.CreateGraphics();
var font = comboBox.Font;
float maxWidth = 0;
foreach (var item in comboBox.Items)
{
maxWidth = Math.Max(maxWidth, g.MeasureString(item.ToString(), font).Width);
}
if (comboBox.Items.Count > comboBox.MaxDropDownItems)
{
maxWidth += SystemInformation.VerticalScrollBarWidth;
}
comboBox.DropDownWidth = Math.Max(comboBox.Width, Convert.ToInt32(maxWidth));
}
IsDesignTime用法:
public class SomeForm : Form
{
public SomeForm()
{
InitializeComponent();
if (this.IsDesignTime())
{
return;
}
// Do something that makes the visual studio crash or hang if we're in design time,
// but any other time executes just fine
}
}
SetDropdownWidth用法:
ComboBox cbo = new ComboBox { Width = 50 };
cbo.Items.Add("Short");
cbo.Items.Add("A little longer");
cbo.Items.Add("Holy cow, this is a really, really long item. How in the world will it fit?");
cbo.SetDropDownWidth();
我忘了说,请随意在Codeplex上使用这些…
讨厌这种代码?
CloneableClass cc1 = new CloneableClass ();
CloneableClass cc2 = null;
CloneableClass cc3 = null;
cc3 = (CloneableClass) cc1.Clone (); // this is ok
cc3 = cc2.Clone (); // this throws null ref exception
// code to handle both cases
cc3 = cc1 != null ? (CloneableClass) cc1.Clone () : null;
它有点笨拙,所以我用这个扩展替换它,我称之为CloneOrNull -
public static T CloneOrNull<T> (this T self) where T : class, ICloneable
{
if (self == null) return null;
return (T) self.Clone ();
}
用法如下:
CloneableClass cc1 = new CloneableClass ();
CloneableClass cc2 = null;
CloneableClass cc3 = null;
cc3 = cc1.CloneOrNull (); // clone of cc1
cc3 = cc2.CloneOrNull (); // null
// look mom, no casts!
请随意在任何地方使用这个!
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。
我最喜欢的是字符串上的IsLike()扩展。IsLike()匹配VB的Like操作符,当你不想写一个完整的正则表达式来解决你的问题时,它很方便。用法是这样的:
"abc".IsLike("a*"); // true
"Abc".IsLike("[A-Z][a-z][a-z]"); // true
"abc123".IsLike("*###"); // true
"hat".IsLike("?at"); // true
"joe".IsLike("[!aeiou]*"); // true
"joe".IsLike("?at"); // false
"joe".IsLike("[A-Z][a-z][a-z]"); // false
下面是代码
public static class StringEntentions {
/// <summary>
/// Indicates whether the current string matches the supplied wildcard pattern. Behaves the same
/// as VB's "Like" Operator.
/// </summary>
/// <param name="s">The string instance where the extension method is called</param>
/// <param name="wildcardPattern">The wildcard pattern to match. Syntax matches VB's Like operator.</param>
/// <returns>true if the string matches the supplied pattern, false otherwise.</returns>
/// <remarks>See http://msdn.microsoft.com/en-us/library/swf8kaxw(v=VS.100).aspx</remarks>
public static bool IsLike(this string s, string wildcardPattern) {
if (s == null || String.IsNullOrEmpty(wildcardPattern)) return false;
// turn into regex pattern, and match the whole string with ^$
var regexPattern = "^" + Regex.Escape(wildcardPattern) + "$";
// add support for ?, #, *, [], and [!]
regexPattern = regexPattern.Replace(@"\[!", "[^")
.Replace(@"\[", "[")
.Replace(@"\]", "]")
.Replace(@"\?", ".")
.Replace(@"\*", ".*")
.Replace(@"\#", @"\d");
var result = false;
try {
result = Regex.IsMatch(s, regexPattern);
}
catch (ArgumentException ex) {
throw new ArgumentException(String.Format("Invalid pattern: {0}", wildcardPattern), ex);
}
return result;
}
}