hi @lightpeak008 , to work with classes you can work with jitclasses, or you can work with extension APIs (either the low-level one or the high-level structref). Jitclasses are easier and unless you really need to go to the extension API, it’s better to start with jitclasses.
The interval class example is the low level extension and by far the hardest to work with. If you need to avoid jitclasses is better to try with structref
You can see an example of using function “pointers” as members of jitclasses here How do I make a jitclass with a jitted function member? and here Typed list of jitted functions in jitclass
hope this helps,
Luk