v('') Vs. apex_application.globalvariable

As i describe in Previous post their are list of global variable which we can use in pl/sql aslo.
Now, Problem is v(' '); is not fix oracle apex may change it in future as they have done it in past so better approach will be use it as apex_application.globalvariable for that i have created a Function as shown below(change it as per need).

Function :

CREATE OR REPLACE FUNCTION GET_CUSTOMERNAME(custid Number) RETURN VARCHAR2 IS
tmpVar VARCHAR2(200);

BEGIN
 
     SELECT FIRST_NAMEINTO tmpVar FROM CUSTOMER WHERE CUST_ID = custid
   and cmp_id = apex_application.g_user;
   RETURN tmpVar;
   EXCEPTION
     WHEN NO_DATA_FOUND THEN
       NULL;
     WHEN OTHERS THEN
       -- Consider logging the error and then re-raise
       RAISE;
END GET_CUSTOMERNAME;
/