Question

Lets say I have a Phone number my classes need to validate and keep track of and for the most part a phone number is just a string so in an attempt to be DRY one would just create a Phone class and inherit from string. Since I can’t do that what is the next best approach? Adding a string as a private member and overloading the equal/= operators so it can be passed and set as a string?

Answer 1

May I suggest that you take Johannes Rudolph’s or C. Ross’s advice. You can also review the behaviour of the implicit keyword which will let you assign in a String-like manner while still doing validation.

i.e.:

public class PhoneNumber {

    private String number;

    public PhoneNumber(String s) {
         // validation code here, throw exception if not valid
         number = s;
    }

    public static implicit operator PhoneNumber(String s) {
         return new PhoneNumber(s);
    }
}