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。
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。
没有检查整个线程,所以它可能已经在这里,但是:
public static class FluentOrderingExtensions
public class FluentOrderer<T> : IEnumerable<T>
{
internal List<Comparison<T>> Comparers = new List<Comparison<T>>();
internal IEnumerable<T> Source;
public FluentOrderer(IEnumerable<T> source)
{
Source = source;
}
#region Implementation of IEnumerable
public IEnumerator<T> GetEnumerator()
{
var workingArray = Source.ToArray();
Array.Sort(workingArray, IterativeComparison);
foreach(var element in workingArray) yield return element;
}
private int IterativeComparison(T a, T b)
{
foreach (var comparer in Comparers)
{
var result = comparer(a,b);
if(result != 0) return result;
}
return 0;
}
IEnumerator IEnumerable.GetEnumerator()
{
return GetEnumerator();
}
#endregion
}
public static FluentOrderer<T> OrderFluentlyBy<T,TResult>(this IEnumerable<T> source, Func<T,TResult> predicate)
where TResult : IComparable<TResult>
{
var result = new FluentOrderer<T>(source);
result.Comparers.Add((a,b)=>predicate(a).CompareTo(predicate(b)));
return result;
}
public static FluentOrderer<T> OrderFluentlyByDescending<T,TResult>(this IEnumerable<T> source, Func<T,TResult> predicate)
where TResult : IComparable<TResult>
{
var result = new FluentOrderer<T>(source);
result.Comparers.Add((a,b)=>predicate(a).CompareTo(predicate(b)) * -1);
return result;
}
public static FluentOrderer<T> ThenBy<T, TResult>(this FluentOrderer<T> source, Func<T, TResult> predicate)
where TResult : IComparable<TResult>
{
source.Comparers.Add((a, b) => predicate(a).CompareTo(predicate(b)));
return source;
}
public static FluentOrderer<T> ThenByDescending<T, TResult>(this FluentOrderer<T> source, Func<T, TResult> predicate)
where TResult : IComparable<TResult>
{
source.Comparers.Add((a, b) => predicate(a).CompareTo(predicate(b)) * -1);
return source;
}
}
用法:
var myFluentlyOrderedList = GetABunchOfComplexObjects()
.OrderFluentlyBy(x=>x.PropertyA)
.ThenByDescending(x=>x.PropertyB)
.ThenBy(x=>x.SomeMethod())
.ThenBy(x=>SomeOtherMethodAppliedTo(x))
.ToList();
... 当然,假设所有的谓词都返回与自身icomcomparable的类型。如果使用像MergeSort这样的稳定排序,而不是。net内置的快速排序,它会更好地工作,但它提供了类似于SQL的可读多字段排序能力(无论如何,它是方法链所能获得的最接近的功能)。您可以通过定义重载来接受比较lambda,而不是基于谓词创建它,从而扩展它以容纳非IComparable的成员。
EDIT: A little explanation, since the commenter got some upticks: this set of methods improves upon the basic OrderBy() functionality by allowing you to sort based on multiple fields in descending order of importance. A real-world example would be sorting a list of invoices by customer, then by invoice number (or invoice date). Other methods of getting the data in this order either wouldn't work (OrderBy() uses an unstable sort, so it cannot be chained) or would be inefficient and not look like it does what you're trying to do.
我创建了一个漂亮的Each扩展,具有与jQuery的Each函数相同的行为。
它允许如下所示,你可以获得当前值的索引,并通过返回false跳出循环:
new[] { "first", "second", "third" }.Each((value, index) =>
{
if (value.Contains("d"))
return false;
Console.Write(value);
return true;
});
下面是代码
/// <summary>
/// Generic iterator function that is useful to replace a foreach loop with at your discretion. A provided action is performed on each element.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="source"></param>
/// <param name="action">Function that takes in the current value in the sequence.
/// <returns></returns>
public static IEnumerable<T> Each<T>(this IEnumerable<T> source, Action<T> action)
{
return source.Each((value, index) =>
{
action(value);
return true;
});
}
/// <summary>
/// Generic iterator function that is useful to replace a foreach loop with at your discretion. A provided action is performed on each element.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="source"></param>
/// <param name="action">Function that takes in the current value and its index in the sequence.
/// <returns></returns>
public static IEnumerable<T> Each<T>(this IEnumerable<T> source, Action<T, int> action)
{
return source.Each((value, index) =>
{
action(value, index);
return true;
});
}
/// <summary>
/// Generic iterator function that is useful to replace a foreach loop with at your discretion. A provided action is performed on each element.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="source"></param>
/// <param name="action">Function that takes in the current value in the sequence. Returns a value indicating whether the iteration should continue. So return false if you don't want to iterate anymore.</param>
/// <returns></returns>
public static IEnumerable<T> Each<T>(this IEnumerable<T> source, Func<T, bool> action)
{
return source.Each((value, index) =>
{
return action(value);
});
}
/// <summary>
/// Generic iterator function that is useful to replace a foreach loop with at your discretion. A provided action is performed on each element.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="source"></param>
/// <param name="action">Function that takes in the current value and its index in the sequence. Returns a value indicating whether the iteration should continue. So return false if you don't want to iterate anymore.</param>
/// <returns></returns>
public static IEnumerable<T> Each<T>(this IEnumerable<T> source, Func<T, int, bool> action)
{
if (source == null)
return source;
int index = 0;
foreach (var sourceItem in source)
{
if (!action(sourceItem, index))
break;
index++;
}
return source;
}
这个还没有完全烤熟因为我们今天早上才想到。它将为Type生成一个完整的类定义。当您有一个大型类,想要创建一个子集或完整定义,但无法访问它的情况下非常有用。例如,将对象存储在数据库中等等。
public static class TypeExtensions
{
public static string GenerateClassDefinition(this Type type)
{
var properties = type.GetFields();
var sb = new StringBuilder();
var classtext = @"private class $name
{
$props}";
foreach (var p in GetTypeInfo(type))
{
sb.AppendFormat(" public {0} {1} ", p.Item2, p.Item1).AppendLine(" { get; set; }");
}
return classtext.Replace("$name", type.Name).Replace("$props", sb.ToString());
}
#region Private Methods
private static List<Tuple<string, string>> GetTypeInfo(Type type)
{
var ret = new List<Tuple<string, string>>();
var fields = type.GetFields();
var props = type.GetProperties();
foreach(var p in props) ret.Add(new Tuple<string, string>(p.Name, TranslateType(p.PropertyType)));
foreach(var f in fields) ret.Add(new Tuple<string, string>(f.Name, TranslateType(f.FieldType)));
return ret;
}
private static string TranslateType(Type input)
{
string ret;
if (Nullable.GetUnderlyingType(input) != null)
{
ret = string.Format("{0}?", TranslateType(Nullable.GetUnderlyingType(input)));
}
else
{
switch (input.Name)
{
case "Int32": ret = "int"; break;
case "Int64": ret = "long"; break;
case "IntPtr": ret = "long"; break;
case "Boolean": ret = "bool"; break;
case "String":
case "Char":
case "Decimal":
ret = input.Name.ToLower(); break;
default: ret = input.Name; break;
}
}
return ret;
}
#endregion
}
使用示例:
Process.GetProcesses().First().GetType().GenerateClassDefinition();
如果使用linqpad,变得更加方便:
Process.GetProcesses().First().GetType().GenerateClassDefinition().Dump();