ON ERROR
|
statement
|
END-ERROR
|
ON ERROR
|
|
statement
|
|
DO statement
DOEND
|
This document covers the following topics:
For an explanation of the symbols used in the syntax diagram, see Syntax Symbols.
Related Statements: DECIDE FOR | DECIDE ON | IF | IF SELECTION
Belongs to Function Group: Processing of Logical Conditions
The ON ERROR statement is used to intercept execution time
errors which would otherwise result in a Natural error message, followed by
termination of Natural program execution, and a return to command input
mode.
When the ON ERROR statement block is entered for execution,
the normal flow of program execution has been interrupted and cannot be resumed
except for error 3145 (record requested in hold), in which case a
RETRY statement will cause processing to be resumed exactly where
it was suspended.
This statement is non-procedural (that is, its execution depends on an event, not on where in a program it is located).
Only one ON ERROR statement is permitted in a Natural
object.
| statement... |
Defining the ON ERROR Processing:
To define the processing that shall take place when an Exiting from an
ON ERROR Block:
An |
|---|---|
| END-ERROR | The Natural reserved word END-ERROR must be used to
end an ON ERROR statement block.
|
When a subroutine structure is built by using
CALLNAT,
PERFORM or
FETCH RETURN, each module
may contain an ON ERROR statement.
When an error occurs, Natural will automatically trace back the
subroutine structure and select the first ON ERROR statement
encountered in a subroutine for execution. If no ON ERROR
statement is found in any module on any level, standard error message
processing is performed and program execution is terminated.
The following Natural system variables can be used in conjunction with
the ON ERROR statement (as shown in the
Example below):
| *ERROR-NR | Contains the number of the error detected by Natural. |
|---|---|
| *ERROR-LINE | Contains the line number of the statement which caused the error. |
** Example 'ONEEX1': ON ERROR
**
**
CAUTION: Executing this example will modify the database records!
************************************************************************
DEFINE DATA LOCAL
1 EMPLOY-VIEW VIEW OF EMPLOYEES
2 NAME
2 CITY
*
1 #NAME (A20)
1 #CITY (A20)
END-DEFINE
*
REPEAT
INPUT 'ENTER NAME:' #NAME
IF #NAME = ' '
STOP
END-IF
FIND EMPLOY-VIEW WITH NAME = #NAME
INPUT (AD=M) 'ENTER NEW VALUES:' ///
'NAME:' NAME /
'CITY:' CITY
UPDATE
END TRANSACTION
/*
ON ERROR
IF *ERROR-NR = 3009
WRITE 'LAST TRANSACTION NOT SUCCESSFUL'
/ 'HIT ENTER TO RESTART PROGRAM'
FETCH 'ONEEX1'
END-IF
WRITE 'ERROR' *ERROR-NR 'OCCURRED IN PROGRAM' *PROGRAM
'AT LINE' *ERROR-LINE
FETCH 'MENU'
END-ERROR
/*
END-FIND
END-REPEAT
END