'===========================================================================
' Subject: OBJECT ORIENTED PROGRAMMING       Date: 04-03-97 (11:45)       
' Author:  Kurt Kuzba                        Code: QB, QBasic, PDS        
' Origin:  FidoNet QUIK_BAS Echo           Packet: MISC.ABC
'===========================================================================
'>   Is there a version of basic that is object oriented?
'>....
'   Not really.
'You can emulate some object techniques, however.
'Inheritance and polymorphism are out, but encapsulation is
'rather possible, using STATIC variables. You cannot put code
'within an object, but you may place the controls within a module
'and use command words as arguments.
'For example... consider a simple UserData class structure.
'This example does not undertake the constructor or destructor
'functions for the data, nor does it attempt to protect the data
'in any way. It does provide a public interface for the access to
'private data. This could be compiled as a module and
'distributed as a separate .OBJ file for linking without giving
'away your coding or methods, just as with a C++ class. There
'would, naturally be an include file with the DECLARE SUB
'prototype so your program could properly access the SUB.

'_|_|_|   OOP.BAS
'_|_|_|   Example of data encapsulation in QB
'_|_|_|   No warrantee or guarantee is given or implied.
'_|_|_|   Released   PUBLIC DOMAIN   by Kurt Kuzba.  (4/3/97)
DECLARE SUB Users (C$, D$, U%)
TYPE UserData
   UName AS STRING * 40
   Age AS INTEGER
   Address AS STRING * 40
   City AS STRING * 25
   State AS STRING * 2
   Zip AS STRING * 9
   Phone AS STRING * 10
END TYPE
CLS
Users "initarray", "", 100
Users "setname", "Your Name Here", 1
Users "setage", STR$(275), 1
Users "setaddress", "1234 Upda Street", 1
Users "setcity", "Anytown_USA", 1
Users "setstate", "ZZ", 1
Users "setzip", "12345-6789", 1
Users "setphone", "(555) 123-4567", 1
Users "getname", Cmd$, 1: PRINT Cmd$; "  (Age:";
Users "getage", Cmd$, 1: PRINT Cmd$; ")"
Users "getaddress", Cmd$, 1: PRINT Cmd$
Users "getcity", Cmd$, 1: PRINT Cmd$; "  ";
Users "getstate", Cmd$, 1: PRINT Cmd$; "  ";
Users "getzip", Cmd$, 1: PRINT Cmd$
Users "getphone", Cmd$, 1: PRINT "Phone: "; Cmd$
Users "cleararray", "", 0
SYSTEM
'_|_|_|   end   OOP.BAS

SUB Users (C$, D$, U%)
   STATIC USR() AS UserData
   SELECT CASE UCASE$(C$)
      CASE "GETNAME": D$ = RTRIM$(USR(U%).UName)
      CASE "GETAGE": D$ = STR$(USR(U%).Age)
      CASE "GETADDRESS": D$ = RTRIM$(USR(U%).Address)
      CASE "GETCITY": D$ = RTRIM$(USR(U%).City)
      CASE "GETSTATE": D$ = RTRIM$(USR(U%).State)
      CASE "GETZIP": a$ = USR(U%).Zip
         D$ = LEFT$(a$, 5) + "-" + MID$(a$, 6)
      CASE "GETPHONE": a$ = USR(U%).Phone
         t$ = "(" + LEFT$(a$, 3) + ") " + MID$(a$, 4, 3)
         D$ = t$ + "-" + MID$(a$, 7)
      CASE "SETNAME": USR(U%).UName = D$
      CASE "SETAGE": USR(U%).Age = VAL(D$)
      CASE "SETADDRESS": USR(U%).Address = D$
      CASE "SETCITY": USR(U%).City = D$
      CASE "SETSTATE": USR(U%).State = D$
      CASE "SETZIP": USR(U%).Zip = LEFT$(D$, 5) + MID$(D$, 7)
      CASE "SETPHONE": USR(U%).Phone = MID$(D$, 2, 3)
         MID$(USR(U%).Phone, 4) = MID$(D$, 7, 3)
         MID$(USR(U%).Phone, 7) = MID$(D$, 11)
      CASE "INITARRAY": DIM USR(1 TO U%) AS UserData
      CASE "CLEARARRAY": ERASE USR
   END SELECT
END SUB