SELECT ILF Statement

Release 5.0.0 of APPX implements the SELECT ILF statement.

SELECT

The SELECT statement allows the access path of in input process to be changed dynamically. The structure of the statement is:

      SELECT  AAA FILENAME                        KEY IS  _____________________________
The application and file name must be specified, even though this statement is relevant only for the Process Control File (PCF). SCAN is available for the key field name, and only defined keys are presented as options.

One reasonable use for the SELECT statement would be to facilitate access path switching by users, without them having to use F3 (SELECT ACCESS PATH), and perhaps in that way limiting which keys they can select. Note that the SELECT statement does not force KEY ENTRY phase, so, without further coding, a user not in KEY ENTRY would see no immediate change in view. It would seem that a valuable use would be to redisplay a scrolling screen using an alternate key, and to do so, the above defined PUSH and POP statements come in very handy. Here's an example:

The file is called TEST42. The primary key is TEST42 ID NO.. Alternate keys are defined as TEST42 CATEGORY and TEST42 REGION. The screen has three buttons defined, linked to User Option 1, 2, and 3. The Option Intercept Event Point contains the following code:

      *     First, we disable the SELECT ACCESS PATH option (F3)
      IF      --- OPTION                    EQ     SELECT ACCESS PATH
T     SET     --- OPTION                     =
      *     Next, use the SELECT statement to set the desired path
      IF      --- OPTION                    EQ     USER 1
T     SELECT  TST TEST42                       KEY IS  TEST42 CATEGORY
F     IF      --- OPTION                    EQ     USER 2
FT    SELECT  TST TEST42                       KEY IS  TEST42 REGION
FF    IF      --- OPTION                    EQ     USER 3
FFT   SELECT  TST TEST42                       KEY IS  TEST42 ID NO
FFF   END
      *     Ignore these buttons if pushed in ADD mode
      IF      --- MODE                      EQ     ADD
T     END
      *     Now, push the options into the stack to switch into KEY ENTRY
      *     and redisplay the records (remember, last in, first out)
      SET     --- OPTION                     =     RETURN
      PUSH    --- OPTION                    FIELD
      *
      IF      --- MODE                      EQ     DELETE
T     SET     --- OPTION                    =      DELETE MODE
F     IF      --- MODE                      EQ     CHANGE
FT    SET     --- OPTION                    =      CHANGE MODE
FF    SET     --- OPTION                    =      INQUIRE MODE
      PUSH    --- OPTION                    FIELD

Finally, just add one line of code to Pre-Display:

      POP     --- OPTION                    FIELD

Also related to this new statement is a new Pre-Defined Field called --- ACCESS PATH. As one might assume, the field contains the value of the current access path for the Process Control File. The field may be viewed, but not changed via ILF code (that is to say, an ILF statement to SET --- ACCESS PATH to a specified value will be ignored).

Limitations:

Comments:

Read what other users have said about this page or add your own comments.

-- SteveFrizzell - 01 Oct 2008

Edit | Attach | Watch | Print version | History: r3 < r2 < r1 | Backlinks | Raw View | Raw edit | More topic actions...
Topic revision: r1 - 2008-10-01 - SteveFrizzell
 
  • Edit
  • Attach
This site is powered by the TWiki collaboration platform Powered by PerlCopyright © 2008-2024 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding TWiki? Send feedback