Syntax allowing factor variables & looping through `varlist'

[Brent McSharry]

I would like to allow factor variable syntax in an ado program. Using auto data, the syntax for the command would look like:

myado foreign i.rep78

Within the ado script, I would then like to loop through each variable with a variant of:

program myado
version 11.0 // version I believe factor variables were introduced
syntax varlist(min=1 numeric fv)
   foreach v of varlist `varlist' {
      markout ...

Of course the code above will result in the error factor variables not allowed r(101);

What is a quick and easy way to expand any factor variables and loop through them (allowing the use of the i. syntax)?

Thank you