Object Oriented QB part 2

 BBS: Inland Empire Archive
Date: 06-08-92 (21:54)             Number: 164
From: PHILIP NELSON                Refer#: NONE
  To: ALL                           Recvd: NO  
Subj: Object Oriented QB part 2      Conf: (2) Quik_Bas

To continue...

There are many other advantages to writing Object Oriented
Code in QuickBasic, and since I've started doing this, I
find that most all programs I write use this concept.

Now, to show one way of implementing Object Oriented
Programming using QB, which is a way I've adopted, although
there can be other methods.

First step.  You need to design the application itself.  This is something
that is taught by most programming classes, but seems to be
relatively unknown in Basic programming.  However, it is a
good idea to do this when creating OOP code, since you'll
more than likely want to re-use the libraries in other
programs.  The one type of object library I create, relates
to IO handling.  The keyboard is a good start, where I have
a few instructions that deal with the keyboard, such as:
KEYPRESS, WAITKEY, GETOPTION, GETNAME, GETPHONE and so on.
Different editors are built into my keyboard object, which
allows me to create applications quickly and without
hastles.

To create the master, or Class library, you need to create a seperate module.
With this module, create an Include file, which will be the
interface between the library and application program.  In
this include file, place the  DECLAREs and any TYPE
definitions required by the library, and that will be
accessed by the application.

To create the KEYBOARD class object, do the following:

Create a function called:  KEYIN$ (Message$)
The next line would contain the following
        GOSUB ParseKeyInWord
        SELECT CASE Word$
               CASE "WAITKEY"
                     DO: A$ = INKEY$: LOOP UNTIL LEN(A$)
                     KEYIN$ = A$
                     EXIT FUNCTION
               CASE "GETOPTION"
                    GOSUB ParseKeyWord
                    IF Len(Word$) = 0 THEN EXIT FUNCTION
                    DO
                        A$ = KEYIN$("WAITKEY")
                    LOOP UNTIL INSTR(Word$, A$)>0
                    KEYIN$ = A$
                    EXIT FUNCTION
               CASE ELSE
        END SELECT
        EXIT FUNCTION
ParseKeyInWord:
ParseKeyWord:      'Spelling error in GETOPTION  process
Message$ = LTRIM$(RTRIM$(Message$))
A = INSTR(Message$+" "," ")
Word$ = LEFT$(Message$+" ",A-1)
Message$ = MID$(Message$+" ",A+1)
Word$ = UCASE$(Word$)
RETURN
END FUNCTION

Continued....

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