Modifying Action Diagrams › Understanding Constructs › Capabilities of Constructs

Capabilities of Constructs

You can nest constructs. For example, you can insert a conditional CASE construct within a REPEAT WHILE construct; in this manner you test for a conditional value while the controlling condition is executed. You can nest sequential actions within any other construct.

  .=REPEAT WHILE
  | |-END OF CURRENT CUSTOMERS NOT REACHED
  | |...Read customers
  | |...
  | |.-CASE
  | |-Order value is *LT 100
  | | ...
  | | ...
  | ‘-ENDCASE
  | ...
  ‘-ENDWHILE

You can exit a construct at any point within the processing logic by means of either one of two built-in functions: *QUIT or *EXIT PROGRAM.

• The *EXIT PROGRAM built-in function allows you to leave the current HLL program or CA 2E external function.
• The *QUIT built-in function allows you to leave the current subroutine logic of the sequential construct block or CA 2E internal function.

There are consequences for using *QUIT and *EXIT PROGRAM within constructs. Other constructs are implemented as inline code within the current subroutine. The *QUIT built-in function allows you to leave the current subroutine logic of the construct block. The *EXIT PROGRAM built-in function allows you to leave the current HLL program.

  .—SEQUENCE

  :  .Order status is Held
  :  ...Review order
  :  .-CASE
  :  |...Order value is RELEASE
  :  |  <--*QUIT
  :  ‘-ENDCASE
  :  ...
  ‘--

For more information on user points, see Understanding Action Diagram User Points at the end of this chapter.