NonNullable example

gistfile1.cs

// NonNullable, the logical inverse of Nullable. Prevents a reference type from being null.
// Implicit conversions to and from the wrapped type provide transparency.
// Usage: Wrap method arguments and/or return values with NonNullable
//
public struct NonNullable<T> where T : class
{
    public readonly T Item;

    public NonNullable(T item)
    {
        if (item == null) throw new ArgumentNullException();
        Item = item;
    }
    public static implicit operator T(NonNullable<T> n)
    {
        return n.Item;
    }

    public static implicit operator NonNullable<T>(T item)
    {
        return new NonNullable<T>(item);
    }
}

class Program
{
    static void Main(string[] args)
    {
        Foo("NOT NULL");
        string s = SafeReference(); //throws
        Foo(null); //throws
    }

    static NonNullable<String> SafeReference()
    {
        return null;
    }

    static void Foo(NonNullable<String> name)
    {
        string safeReference = name;
        Console.WriteLine(safeReference.ToLower());
    }
}

Disclaimer: This is just a proof of concept exercise. I don't use this pattern.