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。
我还没有看到任何关于这个问题的答案…
public static string[] Split(this string value, string regexPattern)
{
return value.Split(regexPattern, RegexOptions.None);
}
public static string[] Split(this string value, string regexPattern,
RegexOptions options)
{
return Regex.Split(value, regexPattern, options);
}
用法:
var obj = "test1,test2,test3";
string[] arrays = obj.Split(",");
WhereIf()方法
var query = dc.Reviewer
.Where(r => r.FacilityID == facilityID)
.WhereIf(CheckBoxActive.Checked, r => r.IsActive);
public static IEnumerable<TSource> WhereIf<TSource>(
this IEnumerable<TSource> source,
bool condition, Func<TSource, bool> predicate)
{
if (condition)
return source.Where(predicate);
else
return source;
}
public static IQueryable<TSource> WhereIf<TSource>(
this IQueryable<TSource> source,
bool condition, Expression<Func<TSource, bool>> predicate)
{
if (condition)
return source.Where(predicate);
else
return source;
}
我还为Where()扩展方法中的索引谓词添加了重载。为了更有趣，可以添加包含额外“else”谓词的风味。
HTH。这些是我的一些主要问题。
using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;
namespace Insert.Your.Namespace.Here.Helpers
{
public static class Extensions
{
public static bool IsNullOrEmpty<T>(this IEnumerable<T> iEnumerable)
{
// Cheers to Joel Mueller for the bugfix. Was .Count(), now it's .Any()
return iEnumerable == null ||
!iEnumerable.Any();
}
public static IList<T> ToListIfNotNullOrEmpty<T>(this IList<T> iList)
{
return iList.IsNullOrEmpty() ? null : iList;
}
public static PagedList<T> ToPagedListIfNotNullOrEmpty<T>(this PagedList<T> pagedList)
{
return pagedList.IsNullOrEmpty() ? null : pagedList;
}
public static string ToPluralString(this int value)
{
return value == 1 ? string.Empty : "s";
}
public static string ToReadableTime(this DateTime value)
{
TimeSpan span = DateTime.Now.Subtract(value);
const string plural = "s";
if (span.Days > 7)
{
return value.ToShortDateString();
}
switch (span.Days)
{
case 0:
switch (span.Hours)
{
case 0:
if (span.Minutes == 0)
{
return span.Seconds <= 0
? "now"
: string.Format("{0} second{1} ago",
span.Seconds,
span.Seconds != 1 ? plural : string.Empty);
}
return string.Format("{0} minute{1} ago",
span.Minutes,
span.Minutes != 1 ? plural : string.Empty);
default:
return string.Format("{0} hour{1} ago",
span.Hours,
span.Hours != 1 ? plural : string.Empty);
}
default:
return string.Format("{0} day{1} ago",
span.Days,
span.Days != 1 ? plural : string.Empty);
}
}
public static string ToShortGuidString(this Guid value)
{
return Convert.ToBase64String(value.ToByteArray())
.Replace("/", "_")
.Replace("+", "-")
.Substring(0, 22);
}
public static Guid FromShortGuidString(this string value)
{
return new Guid(Convert.FromBase64String(value.Replace("_", "/")
.Replace("-", "+") + "=="));
}
public static string ToStringMaximumLength(this string value, int maximumLength)
{
return ToStringMaximumLength(value, maximumLength, "...");
}
public static string ToStringMaximumLength(this string value, int maximumLength, string postFixText)
{
if (string.IsNullOrEmpty(postFixText))
{
throw new ArgumentNullException("postFixText");
}
return value.Length > maximumLength
? string.Format(CultureInfo.InvariantCulture,
"{0}{1}",
value.Substring(0, maximumLength - postFixText.Length),
postFixText)
:
value;
}
public static string SlugDecode(this string value)
{
return value.Replace("_", " ");
}
public static string SlugEncode(this string value)
{
return value.Replace(" ", "_");
}
}
}
public static class EnumerableExtensions
{
[Pure]
public static U MapReduce<T, U>(this IEnumerable<T> enumerable, Func<T, U> map, Func<U, U, U> reduce)
{
CodeContract.RequiresAlways(enumerable != null);
CodeContract.RequiresAlways(enumerable.Skip(1).Any());
CodeContract.RequiresAlways(map != null);
CodeContract.RequiresAlways(reduce != null);
return enumerable.AsParallel().Select(map).Aggregate(reduce);
}
[Pure]
public static U MapReduce<T, U>(this IList<T> list, Func<T, U> map, Func<U, U, U> reduce)
{
CodeContract.RequiresAlways(list != null);
CodeContract.RequiresAlways(list.Count >= 2);
CodeContract.RequiresAlways(map != null);
CodeContract.RequiresAlways(reduce != null);
U result = map(list[0]);
for (int i = 1; i < list.Count; i++)
{
result = reduce(result,map(list[i]));
}
return result;
}
//Parallel version; creates garbage
[Pure]
public static U MapReduce<T, U>(this IList<T> list, Func<T, U> map, Func<U, U, U> reduce)
{
CodeContract.RequiresAlways(list != null);
CodeContract.RequiresAlways(list.Skip(1).Any());
CodeContract.RequiresAlways(map != null);
CodeContract.RequiresAlways(reduce != null);
U[] mapped = new U[list.Count];
Parallel.For(0, mapped.Length, i =>
{
mapped[i] = map(list[i]);
});
U result = mapped[0];
for (int i = 1; i < list.Count; i++)
{
result = reduce(result, mapped[i]);
}
return result;
}
}
我不想添加任何已经说过的东西，所以这里有一些我没有提到的东西。(如果这太长了，对不起):
public static class MyExtensions
{
public static bool IsInteger(this string input)
{
int temp;
return int.TryParse(input, out temp);
}
public static bool IsDecimal(this string input)
{
decimal temp;
return decimal.TryParse(input, out temp);
}
public static int ToInteger(this string input, int defaultValue)
{
int temp;
return (int.TryParse(input, out temp)) ? temp : defaultValue;
}
public static decimal ToDecimal(this string input, decimal defaultValue)
{
decimal temp;
return (decimal.TryParse(input, out temp)) ? temp : defaultValue;
}
public static DateTime ToFirstOfTheMonth(this DateTime input)
{
return input.Date.AddDays(-1 * input.Day + 1);
}
// Intentionally returns 0 if the target date is before the input date.
public static int MonthsUntil(this DateTime input, DateTime targetDate)
{
input = input.ToFirstOfTheMonth();
targetDate = targetDate.ToFirstOfTheMonth();
int result = 0;
while (input < targetDate)
{
input = input.AddMonths(1);
result++;
}
return result;
}
// Used for backwards compatibility in a system built before my time.
public static DataTable ToDataTable(this IEnumerable input)
{
// too much code to show here right now...
}
}
