HP Pascal/iX Programmer's Guide (31502-90023)

7- 3
ANYVAR Parameters
An ANYVAR parameter is similar to a VAR parameter in that its actual
parameter is passed by reference and must be a variable access. If the
routine changes the value of a formal ANYVAR parameter, it changes the
value of the actual parameter.
An ANYVAR parameter differs from a VAR parameter in that its actual
parameter can be of any type. HP Pascal treats the actual parameter as
if it were of the data type of the formal ANYVAR parameter. This is
implicit type coercion.
Example 1
$STANDARD_LEVEL 'HP_MODCAL'$
PROGRAM prog;
TYPE
type1 = ARRAY [1..10] OF integer;
type2 = ARRAY [1..20] OF integer;
type3 = ARRAY [1..11] OF real;
VAR
var1 : type1;
var2 : type2;
var3 : type3;
PROCEDURE p ( VAR parm1 : type1;
ANYVAR parm2 : type2); EXTERNAL;
BEGIN
p(var1, {legal}
var1); {legal}
p(var2, {illegal -- must be of type1}
var2); {legal}
p(var3, {illegal -- must be of type1}
var3); {legal}
END.
The formal VAR parameter parm1 must have an actual parameter of type
type1. The formal ANYVAR parameter parm2 can have an actual parameter of
any type.
The first call to procedure p passes the variable var1 (a 10-element
integer array) to parm2 (a 20-element integer array). This is legal
because parm2 is an ANYVAR parameter; however, parm2[11] through
parm2[20] are undefined. Accessing them causes unpredictable results.
The second call to p passes the variable var2 to parm2. Both are
20-element integer arrays. The procedure p can access all 20 elements of
parm2.
The third call to p passes the variable var3 (an 11-element real array)
to parm2 (a 20-element integer array). Although this is legal, p must
not try to access any of the nonexistent elements parm2[12] through
parm2[20]. The procedure p treats the elements of parm2 as if they were
integers (although the elements of var3 are real).
The implicit type coercion requires that the actual parameter be aligned
on a boundary that is the same or larger than the boundary on which the
formal parameter is aligned (for example, if the formal parameter is
2-byte-aligned, the actual parameter can be 2-byte-aligned or
4-byte-aligned, but it cannot be byte-aligned).
Example 2
PROGRAM prog;
VAR
c : PACKED ARRAY [1..2] OF char;