DSL rule behaves unexpected

[rossko57]

@gert_konemann

Why does the line with Test1, 92 result in ERROR

I think because state objects do not have a subtract operation. You would have to cast it/them as a number first.

@gert_konemann

I expect the same as in Test1, 91

But that will not happen anyway. Items are not variables, when you postUpdate() a new value it is not applied immediately and your rule does not stop and wait for it to happen.

Cumulative rainfall per hour and day. Hour does not work

This is doomed to failure. Item states are not simple variables. postUpdate() is asynchronous, the instruction to perform the update is sent away on openHABs events bus, triggering any rules or bindings that are interested. Eventually, it also updates the Item’s state - but it takes time. Just a few milliseconds. Your rule does not stop and wait. So when you read back the state in the same rule, you will almost certainly get the “old” state. Or you might be lucky, it’s indeterminate. Th…