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。
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();
用于winforms填充组合框:
List<MyObject> myObjects = new List<MyObject>() {
new MyObject() {Name = "a", Id = 0},
new MyObject() {Name = "b", Id = 1},
new MyObject() {Name = "c", Id = 2} }
comboBox.FillDataSource<MyObject>(myObjects, x => x.Name);
扩展方法:
/** <summary>Fills the System.Windows.Forms.ComboBox object DataSource with a
* list of T objects.</summary>
* <param name="values">The list of T objects.</param>
* <param name="displayedValue">A function to apply to each element to get the
* display value.</param>
*/
public static void FillDataSource<T>(this ComboBox comboBox, List<T> values,
Func<T, String> displayedValue) {
// Create dataTable
DataTable data = new DataTable();
data.Columns.Add("ValueMember", typeof(T));
data.Columns.Add("DisplayMember");
for (int i = 0; i < values.Count; i++) {
// For each value/displayed value
// Create new row with value & displayed value
DataRow dr = data.NewRow();
dr["ValueMember"] = values[i];
dr["DisplayMember"] = displayedValue(values[i]) ?? "";
// Add row to the dataTable
data.Rows.Add(dr);
}
// Bind datasource to the comboBox
comboBox.DataSource = data;
comboBox.ValueMember = "ValueMember";
comboBox.DisplayMember = "DisplayMember";
}
我今天刚刚在博客上写了这个。它是INotifyPropertyChanged属性周围的强类型响应式包装器。
GetPropertyValues返回一个IObservable<T>的值,当它们改变时,从当前值开始。如果忽略当前值,可以对结果调用Skip(1)。
用法如下:
IObservable<int> values = viewModel.GetPropertyValues(x => x.IntProperty);
实现:
public static class NotifyPropertyChangeReactiveExtensions
{
// Returns the values of property (an Expression) as they change,
// starting with the current value
public static IObservable<TValue> GetPropertyValues<TSource, TValue>(
this TSource source, Expression<Func<TSource, TValue>> property)
where TSource : INotifyPropertyChanged
{
MemberExpression memberExpression = property.Body as MemberExpression;
if (memberExpression == null)
{
throw new ArgumentException(
"property must directly access a property of the source");
}
string propertyName = memberExpression.Member.Name;
Func<TSource, TValue> accessor = property.Compile();
return source.GetPropertyChangedEvents()
.Where(x => x.EventArgs.PropertyName == propertyName)
.Select(x => accessor(source))
.StartWith(accessor(source));
}
// This is a wrapper around FromEvent(PropertyChanged)
public static IObservable<IEvent<PropertyChangedEventArgs>>
GetPropertyChangedEvents(this INotifyPropertyChanged source)
{
return Observable.FromEvent<PropertyChangedEventHandler,
PropertyChangedEventArgs>(
h => new PropertyChangedEventHandler(h),
h => source.PropertyChanged += h,
h => source.PropertyChanged -= h);
}
}
下面是我用来减少提取单个属性的一些方法:
public static T GetAttribute<T>(this ICustomAttributeProvider provider, bool inherit = false, int index = 0) where T : Attribute
{
return provider.GetAttribute(typeof(T), inherit, index) as T;
}
public static Attribute GetAttribute(this ICustomAttributeProvider provider, Type type, bool inherit = false, int index = 0)
{
bool exists = provider.IsDefined(type, inherit);
if (!exists)
{
return null;
}
object[] attributes = provider.GetCustomAttributes(type, inherit);
if (attributes != null && attributes.Length != 0)
{
return attributes[index] as Attribute;
}
else
{
return null;
}
}
用法(枚举描述hack的实现):
public static string GetDescription(this Enum value)
{
var fieldInfo = value.GetType().GetField(value.ToString());
var attribute = fieldInfo.GetAttribute<DescriptionAttribute>();
return attribute != null ? attribute.Description : null;
}
请随意将其包含在CodePlex项目中!
灵感来自弦。IsNullOrEmpty
要验证给定的List为空或空
public static bool IsNullOrEmpty<TSource>(this List<TSource> src)
{
return (src == null || src.Count == 0);
}
这个是验证给定的两个文件和属性
public static bool Compare(this FileInfo f1, FileInfo f2, string propertyName)
{
try
{
PropertyInfo p1 = f1.GetType().GetProperty(propertyName);
PropertyInfo p2 = f2.GetType().GetProperty(propertyName);
if (p1.GetValue(f1, null) == p2.GetValue(f1, null))
return true;
}
catch (Exception ex)
{
return false;
}
return false;
}
像这样使用它
FileInfo fo = new FileInfo("c:\\netlog.txt");
FileInfo f1 = new FileInfo("c:\\regkey.txt");
fo.compare(f1, "CreationTime");