Question

I have the following:

public static class CityStatusExt
{
    public static string D2(this CityStatus key)
    {
        return ((int) key).ToString("D2");
    }


public static class CityTypeExt
{
    public static string D2(this CityType key)
    {
        return ((int) key).ToString("D2");
    }

Plus other classes with similar extensions that return the key formatted as a “D2”

Is there a way I could inherit from a base class and have the base class provide the functionality so
don’t I don’t have to repeat the same extension method code?

Update. I am sorry I did not mention this but my classes like CityType are Enums.

Answer 1

From the comment below, CityType and CityStatus are enums. Therefore you can do this:

public static class Extensions
{
    public static string D2(this Enum key)
    {
        return Convert.ToInt32(key).ToString("D2");
    }
}

---

Original answer:

You can use a generic method and an interface ID2Able:

public static class Extensions
{ 
    public static string D2<T>(this T key) where T : ID2Able
    { 
        return ((int) key).ToString("D2"); 
    } 
}

This way the extension method won’t show up for absolutely every type; it’ll only be available for things you inherit ID2Able from.