Expression Binding - custom function call

Hi all,

I read about new features in sapui5 - function call in expression binding:

Expression Binding - User Interface Add-On for SAP NetWeaver - SAP Library

On this page is only information, that we should call f(...). I try call my function (from view controler) but without success. Maybe someone has working example how to use this new feature, how to define function in view controler and how to use it in XML View?

I found similar question on: http://stackoverflow.com/questions/31615837/call-controller-function-from-xml-binding-expression

But solution from above page: "{= f(checkSelectedItems, null, ${odata>CustomerId}) }" doesn't work.

Thanks,

Maciej