PL/I condition handling semantics remain supported under Language
Environment; however, the timing of issuing the
run-time message for an ERROR condition with respect to the ERROR
ON-Unit is different in the following way:
- The run-time message for an ERROR condition is issued only if
there is no ERROR ON-Unit established, or if the ERROR ON-Unit does
not recover from the condition by using a GOTO out of block. You can
use a GOTO out of the ERROR ON-Unit to avoid a message for a PL/I ERROR
condition.
For PL/I conditions whose implicit action includes issuing
a message and raising the ERROR condition, the timing of issuing
the message is unchanged.
Table 6 shows when the run-time message for an ERROR
condition is issued under OS PL/I with respect to the ERROR On-Unit.
Table 6. OS PL/I Version 2 Release 3 ERROR ON-Unit and Message for an ERROR condition
|
Condition
|
No
ON-Units
|
ERROR ON-Unit
No GOTO |
ERROR ON-Unit
GOTO
|
| ERROR condition raised1 |
Message |
Message prior to ON-unit |
Message prior to ON-unit |
| ZERODIVIDE condition raised2 |
Message |
Message prior to ON-unit |
Message prior to ON-unit |
|
Notes:
- 1
- Taking the square root of a negative number, data exception,
etc.
- 2
- With no ZERODIVIDE ON-unit; thus, implicit action is taken.
Message is printed, ERROR condition is raised.
|
Table 7 shows when the run-time message
for an ERROR condition is issued under Language Environment with respect to the
ERROR On-Unit.
Table 7. Language Environment ERROR ON-Unit and Message for an ERROR Condition
|
Condition
|
No
ON-units
|
ERROR ON-unit
No GOTO
|
ERROR ON-unit
GOTO
|
| ERROR condition raised1 |
Message |
Message after ON-unit |
No message |
| ZERODIVIDE condition raised2 |
Message |
Message prior to ON-unit |
Message prior to ON-unit |
|
Notes:
- 1
- Taking the square root of a negative number, data exception,
etc.
- 2
- With no ZERODIVIDE ON-unit; thus, implicit action is taken.
Message is printed, ERROR condition is raised.
|
The SNAP traceback message produced by ON ERROR SNAP continues
to be issued before the ERROR ON-unit receives control. The SNAP
traceback message is not identical to the regular ERROR message.
|
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