HOW TO: Using Error Handling in AVR

The information in this article applies to:

ASNA Visual RPG; Release 3.1 and higher
ActiveX
Windows

SUMMARY:

This article will demonstrate on how to use Error Handling in AVR.

STATUS:

Current.

MORE INFORMATION:

In Visual Basic, programmers use the On Error statement. In AVR, error detection is accomplished with the EVAL op-code and the detection and reporting of the error condition are available from the *APP and *ERR built-in objects.

Typically you'll use the *APP object to report Acceler8DB and AS/400 database errors encountered in a database operation by trapping the condition with the ERR indicator. Five properties of this object provide the error number, text, detail and, in AS/400-specific errors, the CPF error.

When working with ActiveX objects, you usually want to trap errors that the object would otherwise raise as a runtime error. Frequently, incorrect parameters in a method are not gracefully handled by the component and it raises an exception rather than returning an error result, for example.

To trap an error, you can use the EVAL statement in RPG/400, RPG IV and Free Format:

For example:

RPG:

C       EVAL       object.method(x, y, z)    88       indicator 88 is
  in ERR column

AVR's Free Format:

Eval F2(object.method(x, y, z)) Err(*IN88)

You can also review the example including in AVR:

Example is called: "Application Error Reporting" and it can be found in the following location: "C:\Program Files\ASNA\Examples\Avr3x\Basics\" (where x is the release number, 1 or 5, etc..)

In AVR 3.5, and higher, you can use the %ERROR built-in function.

TIP: To report or analyze the error, use the *ERR built-in object to retrieve the Error Number, Error Type, Description and Source.

For example, after your EVAL, you can then do this:

msgbox msg(*err.Description + " " + *err.Source)