DHCDP Eval based on class?

So I have a question, I would like to write an if statement based on the classes I have created in dhcpd config. Is this possible? I know I could rewrite all of my original matching statements, but it would simply things if I can evaluate based on class/subclass. I tried a few things based off of the man page, but they don't specifically call out evaluating based on classes.

​

 if (class = "Juniper-ex"){ option ZTP.config-file-name = "juniper/configs/baseex-els-ztp.config"; }