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。
c#中Smalltalk样式的if/else。
您可以自由地在codeplex上使用您使用的任何许可证
using System;
namespace SmalltalkBooleanExtensionMethods
{
public static class BooleanExtension
{
public static T ifTrue<T> (this bool aBoolean, Func<T> method)
{
if (aBoolean)
return (T)method();
else
return default(T);
}
public static void ifTrue (this bool aBoolean, Action method)
{
if (aBoolean)
method();
}
public static T ifFalse<T> (this bool aBoolean, Func<T> method)
{
if (!aBoolean)
return (T)method();
else
return default(T);
}
public static void ifFalse (this bool aBoolean, Action method)
{
if (!aBoolean)
method();
}
public static T ifTrueifFalse<T> (this Boolean aBoolean, Func<T> methodA, Func<T> methodB)
{
if (aBoolean)
return (T)methodA();
else
return (T)methodB();
}
public static void ifTrueifFalse (this Boolean aBoolean, Action methodA, Action methodB)
{
if (aBoolean)
methodA();
else
methodB();
}
}
}
你可能已经有了一个timesRepeat方法。
using System;
namespace SmalltalkBooleanExtensionMethods
{
public static class IntExtension
{
public static int timesRepeat<T>(this int x, Func<T> method)
{
for (int i = x; i > 0; i--)
{
method();
}
return x;
}
public static int timesRepeat(this int x, Action method)
{
for (int i = x; i > 0; i--)
{
method();
}
return x;
}
}
}
Nunit测试
using System;
using SmalltalkBooleanExtensionMethods;
using NUnit.Framework;
namespace SmalltalkBooleanExtensionMethodsTest
{
[TestFixture]
public class SBEMTest
{
int i;
bool itWorks;
[SetUp]
public void Init()
{
i = 0;
itWorks = false;
}
[Test()]
public void TestifTrue()
{
itWorks = (true.ifTrue(() => true));
Assert.IsTrue(itWorks);
}
[Test()]
public void TestifFalse()
{
itWorks = (false.ifFalse(() => true));
Assert.IsTrue(itWorks);
}
[Test()]
public void TestifTrueifFalse()
{
itWorks = false.ifTrueifFalse(() => false, () => true);
Assert.IsTrue(itWorks);
itWorks = false;
itWorks = true.ifTrueifFalse(() => true, () => false);
Assert.IsTrue(itWorks);
}
[Test()]
public void TestTimesRepeat()
{
(5).timesRepeat(() => i = i + 1);
Assert.AreEqual(i, 5);
}
[Test()]
public void TestVoidMethodIfTrue()
{
true.ifTrue(() => SetItWorksBooleanToTrue());
Assert.IsTrue(itWorks);
}
[Test()]
public void TestVoidMethodIfFalse()
{
false.ifFalse(() => SetItWorksBooleanToTrue());
Assert.IsTrue(itWorks);
}
public void TestVoidMethodIfTrueIfFalse()
{
true.ifTrueifFalse(() => SetItWorksBooleanToTrue(), () => SetItWorksBooleanToFalse());
false.ifTrueifFalse(() => SetItWorksBooleanToFalse(), () => SetItWorksBooleanToTrue());
Assert.IsTrue(itWorks);
}
public void TestVoidMethodTimesRepeat()
{
(5).timesRepeat(() => AddOneToi());
Assert.AreEqual(i, 5);
}
public void SetItWorksBooleanToTrue()
{
itWorks = true;
}
public void SetItWorksBooleanToFalse()
{
itWorks = false;
}
public void AddOneToi()
{
i = i + 1;
}
}
}
这是罗马数字的to-and-from。不常用，但可能很方便。用法:
if ("IV".IsValidRomanNumeral())
{
// Do useful stuff with the number 4.
}
Console.WriteLine("MMMDCCCLXXXVIII".ParseRomanNumeral());
Console.WriteLine(3888.ToRomanNumeralString());
源:
public static class RomanNumeralExtensions
{
private const int NumberOfRomanNumeralMaps = 13;
private static readonly Dictionary<string, int> romanNumerals =
new Dictionary<string, int>(NumberOfRomanNumeralMaps)
{
{ "M", 1000 },
{ "CM", 900 },
{ "D", 500 },
{ "CD", 400 },
{ "C", 100 },
{ "XC", 90 },
{ "L", 50 },
{ "XL", 40 },
{ "X", 10 },
{ "IX", 9 },
{ "V", 5 },
{ "IV", 4 },
{ "I", 1 }
};
private static readonly Regex validRomanNumeral = new Regex(
"^(?i:(?=[MDCLXVI])((M{0,3})((C[DM])|(D?C{0,3}))"
+ "?((X[LC])|(L?XX{0,2})|L)?((I[VX])|(V?(II{0,2}))|V)?))$",
RegexOptions.Compiled);
public static bool IsValidRomanNumeral(this string value)
{
return validRomanNumeral.IsMatch(value);
}
public static int ParseRomanNumeral(this string value)
{
if (value == null)
{
throw new ArgumentNullException("value");
}
value = value.ToUpperInvariant().Trim();
var length = value.Length;
if ((length == 0) || !value.IsValidRomanNumeral())
{
throw new ArgumentException("Empty or invalid Roman numeral string.", "value");
}
var total = 0;
var i = length;
while (i > 0)
{
var digit = romanNumerals[value[--i].ToString()];
if (i > 0)
{
var previousDigit = romanNumerals[value[i - 1].ToString()];
if (previousDigit < digit)
{
digit -= previousDigit;
i--;
}
}
total += digit;
}
return total;
}
public static string ToRomanNumeralString(this int value)
{
const int MinValue = 1;
const int MaxValue = 3999;
if ((value < MinValue) || (value > MaxValue))
{
throw new ArgumentOutOfRangeException("value", value, "Argument out of Roman numeral range.");
}
const int MaxRomanNumeralLength = 15;
var sb = new StringBuilder(MaxRomanNumeralLength);
foreach (var pair in romanNumerals)
{
while (value / pair.Value > 0)
{
sb.Append(pair.Key);
value -= pair.Value;
}
}
return sb.ToString();
}
}
字符串。格式的快捷方式:
public static class StringExtensions
{
// Enable quick and more natural string.Format calls
public static string F(this string s, params object[] args)
{
return string.Format(s, args);
}
}
例子:
var s = "The co-ordinate is ({0}, {1})".F(point.X, point.Y);
要快速复制粘贴，请点击这里。
难道你不觉得输入“一些字符串”. f(“param”)而不是字符串更自然吗?格式(“一些字符串”，“参数”)?
想要一个更容易读懂的名字，试试下面的建议:
s = "Hello {0} world {1}!".Fmt("Stack", "Overflow");
s = "Hello {0} world {1}!".FormatBy("Stack", "Overflow");
s = "Hello {0} world {1}!".FormatWith("Stack", "Overflow");
s = "Hello {0} world {1}!".Display("Stack", "Overflow");
s = "Hello {0} world {1}!".With("Stack", "Overflow");
..
