Live template variable expression depending on other variable

I am trying to create a live template for an Angular service:

angular.service("$serviceName$", $serviceNameUpper$);

I would like to have "serviceNameUpper" be the capitalized version of "serviceName".

I tried setting both "Expression" and "Default Value" to capitalize($serviceName$), with and without the "Skip if defined" checkbox checked, but it doesn't seem to have any effect - the variable is not expanded.

Is this possible?