multiple classes with same methods - best pattern

Question

I have a few classes in my current project where validation of Email/Website addresses is necessary. The methods to do that are all the same.

I wondered what's the best way to implement this, so I don't need to have these methods copy pasted everywhere?

The classes themselves are not necessarily related, they only have those validation methods in common.

Answer 1

You might want to put all the validation code into a Validator class, then use that class anywhere that validation is needed. Access to validation should be through a single method, Validate(object Something) maybe. I think this is called "Composition" (as far as design patterns go).

Later on, you can have sub-classes of Validator that maybe more specific or do different kinds of validation.

You could also have all classes requiring validation extend a base class or abstract class that has 90% of the validation in it.

Answer 2

How about adding an interface, and using an extension method?

public interface IFoo { }

public class A : IFoo {}
public class B : IFoo {}
public class C : IFoo {}

public static class FooUtils {
    public static void Bar(this IFoo foo) { /* impl */ }
}

That way:

• no unnecessary inheritance
• no duplication

Answer 3

Sounds like you just need a static class with a static method

public static class Utilities{
    public static bool validEmail(string email)
    {
        //Your code here
    }
}