Allow property indirection ${value(variable)}

[rhaschke]

Unfortunately, due to limitations of the property expression parser, we cannot implement property indirection, i.e. having a property variable that holds the name of the actual property one wants to access: ${${variable}}.
However, that's a crucial feature I missed multiple times in the past. One idea is to expose a function, e.g. value() which performs the indirection on the python level - without the need to adapt the expression parser: ${value(variable)}

[gavanderhoorn]

Isn't this another instance of "double evaluation is not supported"?

[rhaschke]

Yes, exactly.