We need to be able to modify the logic in the get next work based on a value in the declare expression . The extension point that we see is the List view GetNextWork but that view is deprecated and also doesn't seem to work with Declare expressions. We are also unable to use a function alias so would like to know what Pega recommends to use in this situation
Get next work is definitely customizable. I don't recall the rules involved off the top of my head, but I'd start by running tracer and hitting GNW as it is now to see what rules are called and what logic is used. In the abstract, a declare expression seems reasonable, but if you dig into the code as it is running, you may find that there are easier ways to filter the items to get the right work based on your business logic.