Cancel, Suspend, Resume, Retry

CANCEL, SUSPEND and RESUME are all handy debugging commands. RETRY is a cousin to RETURN and is useful in error handlers.

Usage

CANCEL
SUSPEND
RESUME
RETRY

CANCEL kills program execution on the spot. We use it most when we’re in the middle of debugging and figure out what the problem is. We cancel the program, go fix the bug and try again. Some folks use it to end applications, but it’s not a particularly graceful exit—use RETURN instead.

SUSPEND and RESUME let you stop and restart a program. We haven’t used SUSPEND much since the Trace window came along, but, once in a while, it’s handy to be able to arrange for execution to stop at a particular point. RESUME we use a lot, though it’s often from the Debugger menu. Actually, we’re far more likely to press F5 or click on the green Resume button than to type the command or choose it from the menu. Regardless of how you issue it, though, RESUME picks up execution where you left off.

RETRY is an interesting command. It works like RETURN, except that it goes back to the command that got you there instead of the one after it. Using RETRY where you shouldn’t is a quick ticket to an infinite loop.

However, in an error handler, RETRY is worth a million bucks. You can return to the statement that caused the error and try the operation again. This is useful for things like failed locks. You can also use it for situations where you’ve fixed the problem in the meantime (say, by re-creating a missing file).

Example

* This program lets you test these commands

WAIT WINDOW "In program. Press a key."
WAIT WINDOW "Type RESUME to go on" NOWAIT
SUSPEND

WAIT WINDOW "Back in program"

DO sub1

WAIT WINDOW "Back from sub1"

RETURN

PROC sub1
* See the difference between Return or Retry
* Enter "E" for Retry or something other than
* "R" to get out immediately.

WAIT WINDOW "(R)eturn or R(e)try" TO cGoOn

DO CASE
CASE UPPER(cGoOn)="R"
   RETURN
CASE UPPER(cGoOn)="E"
   RETRY
OTHERWISE
   CANCEL
ENDCASE

RETURN

See Also

Return