T in class? AddRange ICollection?

Question

I try to do static class, add to icollection but i got some issues i cant seem to overcome. that is how i get so i can pass a ICollection in the method? cause T is that say

Answer 1

No, ICollection doesn't have an AddRange method - and even if it did, you'd be trying to dereference null which will throw a NullReferenceException. You haven't specified a collection to add the list to... what exactly are you trying to do?

You could create (say) a new List - and that has the benefit of already having a constructor which can take an IEnumerable:

public static ICollection Add(this IEnumerable list)
{
    return new List(list);            
}

However, at that point you've really just reimplemented Enumerable.ToList() and given it a different return type...

If you want to add everything to an existing collection, you might want something like this:

public static ICollection AddTo(this IEnumerable list,
                                      ICollection collection)
{
    foreach (T item in list)
    {
        collection.Add(item);
    }
    return collection;
}