IBM AS/400 manual Using Exception Handlers, Exception Handler Priority, Nested Exceptions

Using Exception Handlers

Using Exception Handlers

Planning the exception handling capability of your application means maki following decisions:

1.Decide if you will use the RPG-specific means of handling errors indicator, 'E' extender, or error subroutine) or whether you will

exception	handling routine			which	you will	register		using	the ILE API
You might	also	choose	to	use	both.
2. Decide	on the	recovery		action, that		is,	where	the	program will
essing if	you	use a	separate		exception		handling	routine.

In addition, keep in mind the following when planning your exception ha

¹ Priority of handlers

¹Nested exceptions

¹ Default actions for unhandled exceptions

¹Effect of optimization level

Exception Handler Priority

Exception handler priority becomes important if you use both language- error handling and ILE condition handlers. For an ILE RPG procedure, e handlers have the following priority:

1. Either an error indicator or an 'E' extender handler

2. ILE condition handler

3. I/O error	subroutine handler (for file errors)		and Program	error
handler (for	all other	errors)
4. RPG default	handler for	unhandled exceptions (main	procedure	only)

Nested Exceptions

Exceptions can be nested. A nested exception is an exception that another exception is being handled. When this happens, the processing exception is temporarily suspended. Exception handling begins again wit recently generated exception.

Unhandled Exceptions

An unhandled exception is one that has not been handled by an exce associated with the call stack entry that first received the exce

exception	is unhandled, one of	the following actions		occurs:
If the message	type is a function check	(CPF9999)	associated	with a main pro-

cedurethen the RPG default handler will issue an inquiry message des originating condition.

¹If you pick the D(ump) or C(ancel) option then the procedure whi received the exception terminates and the function check is perc caller.

¹If you pick the R(etry) or G(et Input) option then the function exception processing ends, and the procedure resumes processing a (when G is chosen) or at the I/O operation in which the except

Chapter 12. Handling Exceptions223