pTAL Reference Manual (H06.03+)

Built-In Routines

HP pTAL Reference Manual—523746-005

15-73

$OPTIONAL

$OPTIONAL controls whether a given parameter or parameter pair is passed to a

VARIABLE procedure or EXTENSIBLE procedure.

cond-expression

is a conditional expression

. If cond-expression is true, param or param-pair

is passed. If cond-expression is false, param (or param-pair ) is not

passed.

param

is an a variable identifier or an expression

that defines an actual parameter to pass

to a formal parameter declared in the called procedure if cond-expression is

true.

Example 15-67. $OFFSET Routine Applied to a Template Structure

INT x;

STRUCT st[-1:1];

BEGIN

INT item;

FIXED(2) price;

END;

x := $OFFSET (st[-1].item); !x gets -10

pTAL privileged procedure No

Can be executed only by privileged procedures No

Sets condition code No

Sets $CARRY No

Sets $OVERFLOW No

$OPTIONAL

( cond-expression , param

param-pair

)

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