Determining name of the variable passed to function

If I pass variable as a positional argument to a function, is it possible to determine the name of the variable used from inside the function, or I can only access its value? I have a function envir-export that I can use to define an environment variable and store it in a special environment file that would then get sourced. envir-export () { nm="$1" vl="$2" envirs_trkrc="${HOME}/Opstk/envirs" echo "export ${nm}=${vl}" >> ${envirs_trkrc}/envirs.rc source ${envirs_trkrc}/envirs.rc echo "$nm exported with value $vl" } Currently I am using by the following call envir-export VERBOS 8 Using the name VERBOS with value 8. I would like to improve on this function, both in convenience, and also functionally. For instance, if no value is supplied then I only export the name with a value being assigned.