EXTENT statement

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 ]

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 */

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.

See also 

DEFINE PARAMETER statement, DEFINE VARIABLE statement, EXTENT attribute, EXTENT function, Parameter definition syntax