Scala - extends vs with

Question

I am confused. In my existing project, I am not able to find the difference between extends and with. Could you please help me?

Answer 1

The first thing you inherit from can either be a trait or a class, using the extends keyword.

trait SomeTrait
class SomeClass

class ThisIsValid extends SomeTrait
class ThisAsWell extends SomeClass

You can define further inherited traits (and only traits) using the with keyword.

class AlsoThisWorks extends SomeClass with SomeTrait

If a trait inherits from a class you cannot use it like in the above example.

That's it regarding the extends and with keywords. If you want to learn more about classes and traits the official documentation goes in depth on the topic.