Fixes the extent (number of elements) for an
unfixed indeterminate array variable or parameter. ABL treats the
fixed indeterminate array as a determinate array consistent with
its data type.
Syntax
EXTENT ( array ) = expression [ NO-ERROR ]
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-
array
- A CHARACTER expression that evaluates to the name of an unfixed indeterminate
array variable or parameter.
-
expression
- An INTEGER expression that evaluates to the extent value assigned to
the array variable or parameter. The extent value can be any number between
1 and 28000, inclusive.
- NO-ERROR
- Suppresses ABL errors or error messages that would otherwise occur and diverts them to
the ERROR-STATUS system handle. If an error occurs, the action of
the statement is not done and execution continues with the next statement. If the
statement fails, any persistent side-effects of the statement are backed out. If the
statement includes an expression that contains other executable elements, like methods,
the work performed by these elements may or may not be done, depending on the order the
AVM resolves the expression elements and the occurrence of the error.
To check for
errors after a statement that uses the NO-ERROR option:
- Check the ERROR-STATUS:ERROR attribute to see if the AVM raised the ERROR
condition.
- Check if the ERROR-STATUS:NUM-MESSAGES attribute is greater than zero to see if
the AVM generated error messages. ABL handle methods used in a block without
a CATCH end block treat errors as warnings and do not raise ERROR, do not set the
ERROR-STATUS:ERROR attribute, but do add messages to the ERROR-STATUS system handle.
Therefore, this test is the better test for code using handle methods without CATCH
end blocks. ABL handle methods used in a block with a CATCH end block raise
ERROR and add messages to the error object generated by the AVM. In this case, the
AVM does not update the ERROR-STATUS system handle.
- Use ERROR-STATUS:GET-MESSAGE( message-num ) to retrieve a
particular message, where message-num is 1 for the first
message.
If the statement does not include the NO-ERROR option, you can use a CATCH end
block to handle errors raised by the statement.
Some other important usage notes
on the NO-ERROR option:
- NO-ERROR does not suppress errors that raise the STOP or QUIT condition.
- A CATCH statement, which introduces a CATCH end block, is analogous to a NO-ERROR
option in that it also suppresses errors, but it does so for an entire block of
code. It is different in that the error messages are contained in a class-based
error object (generated by the AVM or explicitly thrown), as opposed to the
ERROR-STATUS system handle. Also, if errors raised in the block are not handled by a
compatible CATCH block, ON ERROR phrase, or UNDO statement, then the error is not
suppressed, but handled with the default error processing for that block type.
- When a statement contains the NO-ERROR option and resides in a block with a CATCH
end block, the NO-ERROR option takes precedence over the CATCH block. That is, an
error raised on the statement with the NO-ERROR option will not be handled by a
compatible CATCH end block. The error is redirected to the ERROR-STATUS system
handle as normal.
- If an error object is thrown to a statement that includes the NO-ERROR option,
then the information and messages in the error object will be used to set the
ERROR-STATUS system handle. This interoperability feature is important for those
integrating code that uses the traditional NO-ERROR technique with the newer,
structured error handling that features error objects and CATCH end blocks.
Example
The
following example defines an unfixed indeterminate array variable
and fixes its dimension using the EXTENT statement:
DEFINE VARIABLE x AS INTEGER NO-UNDO EXTENT.
MESSAGE EXTENT(x). /* Function returns ? */
EXTENT(x) = 4. /* Statement fixes the extent to 4 */
MESSAGE EXTENT(x). /* Function returns 4 */
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Notes
- You
can also use the EXTENT statement to reset a fixed indeterminate
array (that was previously defined as an unfixed indeterminate array)
to its previously unfixed state by specifying the Unknown value (?) in expression.
- If you call the EXTENT statement attempting to fix the extent
of a determinate or fixed indeterminate array variable or parameter,
the AVM generates a run-time error. Consider first using the EXTENT
function to determine if an array variable or parameter is already fixed.
