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The system function
POS(field-name) returns an
identification of the field whose name is specified with the system function.
The value returned is an internal representation of the field address.
POS(field-name) may be used to
identify a specific field, regardless of its position in a map. This means that
the sequence and number of fields in a map may be changed, but
POS(field-name) will still uniquely
identify the same field. With this, for example, you need only a single
REINPUT statement to make the field to be MARKed
dependent on the program logic.
Example:
DECIDE ON FIRST VALUE OF ...
VALUE ...
COMPUTE #FIELDX = POS(FIELD1)
VALUE ...
COMPUTE #FIELDX = POS(FIELD2)
...
END-DECIDE
...
REINPUT ... MARK #FIELDX
If the field specified with POS is an array, a specific
occurrence must be specified; for example, POS(FIELDX(5)).
POS cannot be applied to an array range.
Note:POS cannot distinguish between two different variables
that start at the same storage position (REDEFINE variables) since the
internal field address returned by POS is the same
for both.
The system function
POS(field-name) may be used in
conjunction with the Natural system variable
*CURS-FIELD
to make the execution of certain functions dependent on which field the cursor
is currently positioned in.
*CURS-FIELD contains the internal
identification of the field in which the cursor is currently positioned; it
cannot be used by itself, but only in conjunction with
POS(field-name). You may use them to
check if the cursor is currently positioned in a specific field and have
processing performed depending on that condition.
Example:
IF *CURS-FIELD = POS(FIELDX) MOVE *CURS-FIELD TO #FIELDY END-IF ... REINPUT ... MARK #FIELDY
Notes:
*CURS-FIELD and
POS(field-name) serve only as internal
identifications of the fields and cannot be used for arithmetic operations.
POS(field-name) for an occurrence of an
X-array (an array for which
at least one bound in at least one dimension is specified as expansible) may
change after the number of occurrences for a dimension of the array has been
changed using the EXPAND,
RESIZE or
REDUCE
statements.
*CURS-FIELD and
POS(field-name) refer to a context
variable, the resulting information can only be used within the same
conversation.
*CURS-FIELD identifies the operand that represents
the value of the control that has the input focus. You may use
*CURS-FIELD in conjunction with the
POS function to check for the control that has the input focus and
perform processing depending on that condition.
*CURS-FIELD and
POS(field-name) cannot distinguish
between two different variables that start at the same storage position
(REDEFINE variables)
since the internal field addresses returned by
*CURS-FIELD and
POS(field-name) are the same for both
variables.
See also Dialog Design, Field-Sensitive Processing and Simplifying Programming in the Programming Guide in the Programming Guide.
