There options for doing fancy java-isms from clojure, but sometimes it's easier to just write a bit of java in your clojure project for the non-trivial interop.

Otherwise, which method you use kind of depends on what problem you're trying to solve and why you're trying to extend a class while adding an instance field.

Yeah, I was suspecting that straight Java might be easier.

What I am trying to do is to create a record that will store initialisation parameters for Java object and have it implement component/Lifecycle protocol. Upon component startup I need it to return new object extending a Java class but with additional field carrying over the original object with init params so this original object can be returned after the stop is called on component.

You can close over state by defining an atom with a let and then create the proxy object using proxy which can access and mutate the atom

proxy lets you extend a class and interfaces.

i’m away from keyboard, but i can try to give an example later

But won’t the state atom be shared across all instances of this protocol?

Problem I see with proxy is that I don't think I can add new method.

Only overwrite existing one.

not sure what you mean by add a new method. you can always create an interface with the method you want and implement it

I would give some example code, but I'm not totally sure I understand the goal

Yeah, actually I did it the other way around. Burnt too much time here already.

Thank you for help though!

As a type hint, yes

and where aren't they equivalent? Since it looks like they also work the same for selecting methods as values

As a value