Specman reflection: How to get the value of simple port, when its name is given as a string?

I need to get the value of a simple port, while the only information I have is the port's name (as a string). Something like this:

my_meth(port_type : string) is { //e.g.: port_type = "signal_map.some_port$"
    var rf_port_val : rf_value_holder = rf_manager..??? //How to get port's value by its name using port_type?

    // do something...
};

How can it be done? In addition, I could not find any useful documentation about Specman reflection, may be you can refer me to such? Thank you for any help.