It’s not possible, at least not in v7.9. I’ve been meaning to check what is exposed in v8’s expression tags by my objectScript() function’s binding argument. The new tag group functionality suggests it won’t be null.
But when the values change (either when written from the input field, or read from source), the script doesn’t appear to run. When I change it to the following:
if({Root Container.Numeric Text Field 5.floatValue} < {Root Container.Numeric Text Field 5.minimum},
"Red", "White")
then it functions as expected, triggering whenever the values update.
Expected and unavoidable behavior, just like with runScript(). binding.target is intended for values you can’t get to any other way, or you deliberately want to exclude from re-triggering. Use the args feature to pass dynamic values to the python expression.
Keep in mind that both runScript and objectScript have overhead from starting a python environment that pure expressions do not. Use them where other techniques are insufficient, and especially avoid changing the python expression string itself.