The function "doforeach" allows me to call a function by string. I use

Stefan, can you provide a little more context as to what you are trying to achieve?

Could you please describe the use case for using the apply function? In most cases, it should be a great alternative.

Sure. I have a process dashboard on which I want to display some data. The process itself can be of several "kinds". For each kind I have a expression rule that renders some HTML to be displayed on the dashboard. In the PV I save the name of this function and call it dynamically using "doforeach" with a single item list. This works now since nearly 3 years.

Apply does not allow me to use a string as the function to call.

You should save your function as an expression rule and call the new expression rule in your apply() function.

Specifically, instead of doforeach("myexpression", pv!parameters) it will be apply(rule!myexpression,pv!parameters)

You could use nested ifs.

=if(pv!processKind="a", apply(rule!ruleA), if(pv!processKind="b",apply(rule!ruleB),if(pv!processKind="c",apply(rule!ruleC),"etc")))

My current rule looks like this

doforeach(ri!extension.display_function, {ri!data})

and it does axectly what I want. My dashboard is part of a framework for a generic ticket management system and by using dynamic function call with doforeach I have an easy way to show different content on the dashboard.

Being able to cast a string to a function reference would solve my problem :-)

Please state what version you are using.