Is there a way to write an Extension Method that applies to multiple types?

Question

I'm trying to write an extension method that will add the function HasFactor to the class int in C#. This works wonderfully, like so:

static class ExtendInt
{
    public static bool HasFactor(this int source, int factor)
    {
        return (source % factor == 0);
    }
}

class Program
{
    static void Main()
    {
        int i = 50;
        int f = 2;
        bool b = i.HasFactor(f);
        Console.WriteLine("Is {0} a factor of {1}? {2}",f,i,b);
        Console.ReadLine();
     }
}

This works great because variable i in the Main() method above is declared as an int. However, if i is declared as an Int16 or an Int64, the extension method does not show up unless it is explicitly cast as an int or Int32.

I now would like to apply the same HasFactor method to Int16 and Int64. However, I'd rather not write separate extension methods for each type of int. I could write a single method for Int64 and then explicitly cast everything as an Int64 or long in order for the extension method to appear.

Ideally, I'd prefer to have the same extension method apply to all three types without having to copy and paste a lot of code.

Is this even possible in C#? If not, is there a recommended best-practice for this type of situation?

Answer 1

No, this is not possible in C#. You'll have to create one extension method for each type. The closest is to have an extension method that operates on an interface, but in this case there is no INumeric interface or anything similar that is implemented by the various numeric types.