我有以下代码,我正在.NET 4.0项目中编译
public static class Ext
{
public static IEnumerable<T> Where(this IEnumerable<T> source,Func<T,bool> predicate)
{
if (source == null)
{
throw new ArgumentNullException("source");
}
if (predicate == null)
{
throw new ArgumentNullException("predicate");
}
return WhereIterator(source,predicate);
}
private static IEnumerable<T> WhereIterator(IEnumerable<T> source,bool> predicate)
{
foreach (T current in source)
{
if (predicate(current))
{
yield return current;
}
}
}
}
但是得到以下错误.我的System.dll已被默认包含在引用中.我可能做错了什么？
Error 1 The type or namespace name 'T' could not be found (are you missing a using directive or an assembly reference?) Error 2 The type or namespace name 'T' could not be found (are you missing a using directive or an assembly reference?) Error 3 The type or namespace name 'T' could not be found (are you missing a using directive or an assembly reference?)
解决方法
尝试：
public static IEnumerable<T> Where<T>(this IEnumerable<T> source,bool> predicate)
和
private static IEnumerable<T> WhereIterator<T>(IEnumerable<T> source,bool> predicate)
简而言之,您在方法签名中缺少通用T声明(其中所有其他T都被推断).
