Question

I have a class Product : IProduct. All the code that uses products works with interfaces, interface implementation is supplied by an in-house DI container. What do I need to add to the interface and the class, so I can write code like:

IProduct defectiveSku;

IProduct customerSku;

….

if(customerSku == devectiveSku)

{

// refund, blame someone else

}

else

{

// scare the customer away

}

Answer 1

You can use the IEquatable<T> interface:

interface IProduct : IEquatable<IProduct> { ... }

But you’ll have to compare with the Equals method:

if (customerSku.Equals(defectiveSku)) ...

Comparing with Equals is better for an entity like IProduct because it better conveys the semantics of entity equality than the == operator; which normally conveys just reference equality or value equality.