DEV Community


Discussion on: Refactoring: My 6 favorite patterns

richardcochrane profile image
Richard Cochrane

That's a good point Marian and the crux behind the composition vs inheritance thinking but I think there's a place for both. My main decider (and it's beside the point to the one the author is making) is asking if that method really belongs on the class. So classes inheriting from Animal (Dolphin, Cat, Elephant) would all "make sound" (their own sound) so that would be a great case for inheritance but if the functionality is not related, eg. "send mail" (sorry, it's contrived but let's say in a talking animals universe, like Zootropolis, where animals can send letters either by running, flying or the postal service), the sending of emails is not intrinsic to being an animal and the same functionality could be rightfully applied to companies, people and other types of class that don't inherit from Animal, then composition is a better way to go. In my opinion, of course :-)

gkatsanos profile image
George Katsanos • Edited

reading both the original recommendation as well as the alternative, I really have a strong feeling to stick with the conditions. Also, why not move simply move/abstract the condition inside the sendmail function? The information we need is already inside the user object. I find creating the extra classes for each type of favorite food overengineered TBH. And adding one new favorite food type, means we need a whole new class for it?

sendEmail(user) { return `<div>Hey ${user.firstName}, we saw you like ${}</div>` };