IEnumerable的AddItem的C＃扩展方法<T>

Question

使用扩展方法将项目添加到IEnumerable集合的最佳方法是什么？

Answer 1

enumerable.Concat(new[]{ objToAdd })

Answer 2

You cannot (directly). The purpose of the interface is to expose an enumerator.

Edit : You would have to convert the IEnumerable to another type (like a List ) or concatenation to add, which would result not in adding to an existing IEnumerable , but concatenating to a new IEnumerable instead.

The only option would be to test if the if it implements any of the interfaces usable for adding like IList, ICollection, IDictionary, ILookup, ... and even then you won't be sure that you can add to an existing IEnumerable .

Answer 3

I have this in my IEnumerableExtensions class, not sure its too efficient, but I use it very sparingly.

public static IEnumerable<T> Add<T>(this IEnumerable<T> enumerable, T item)
{
   var list = enumerable.ToList();
   list.Add(item);
   return list;
}