#my idea

%character_tests{ "var1" , "^0-9",
                  "var2" , "^A-Za-z0-9\." );

#object update nethod
# ARGS: variable name , variable value
# RETURNS: 1 if sucessful, undef if not
# sets error vars not described here
sub update( $ )
{
   if( $_[0] =~ /$character_tests{ $_[0] )/ ) 
   {
      &set_error_type = "illegal characters";
   }
   else
   {
       $self->{var1} = $_[0];
   }

}