Miscellany

public interface IPAddress {
    // ...
}

public class IP4Address : IPAddress {
    // ...

    public static bool TryParse(string text, out IP4Address address) {
        // ...
    }
}

public static class IPAddressFactory {
    public static bool TryParse(string text, out IPAddress address) {
        address = null;

        if (IP4Address.TryParse(text, out address)) { // CS1503
            return true;
        }

        return false;
    }
}