[Mono-dev] Trivial Enumerable Optimizations

[Miguel de Icaza]

> So is it possible to further optimize the LongCount() extension method?
> Perhaps something like this?
> 
>     public static long LongCount<TSource> (this IEnumerable<TSource> source)
>     {
>        // as before...
>        ICollection<TSource> c = source as ICollection<TSource>;
>        if (c != null) {
>            try {
>                return c.Count;
>            }
>            catch {
>                // ignore; collection has > int.MaxValue elements, 
>                // so count manually below.
>            }
>        }
>        // as before...
>     }

The problem is that there is no such rule that states that c.Count will
throw an exception if it has more than certain number of elements.

Miguel.