Question

After reviewing this answer and given the extension method:

public static bool IsIn<T>(this T source, params T[] list)
{
    if(null == source) throw new ArgumentNullException("source");
    return list.Contains(source);
}

What are your favorite extension methods for C#? (codeplex.com/extensionoverflow)

Is it better to write another extension method that would check if a variable is not in a list such as if(x.IsNotIn(1,2,3)) or is it better to just negate the first extension method such as if(!x.IsIn(1,2,3))?

Answer 1

I prefer negation of the positive case method. Why rewrite or clipboard inherit?