Re: options(*varsize)

[Joep Beckeringh <joep@xxxxxxxxxxxxxxxxxxx>]

Brian,

When you pass a parameter by reference (default), all that is actually passed is 
the pointer to the parameter. If you don't specify OPTIONS(*VARSIZE) the 
compiler checks whether the parameter you are passing matches the length that is 
defined in the prototype. If you do specify OPTIONS(*VARSIZE), you tell the 
compiler that it does not have to check the length. Obviously the procedure has 
to have a way to know the actual length of the parameter being passed. One way 
is to have an extra parameter for the length (as most APIs have); another way is 
to use a VARYING length parameter.

Joep Beckeringh


brian wrote:
> I'm writing a procedure that's a nicer interface to cvthc. cvthc's
> parameters are two pointers and an integer. In the fields of my
> procedure's prototype, I don't want to specify some arbitrary field length
> limit. I basically want to pass two pointers and an integer indicating the
> length of one of the fields. I originally coded it exactly like that, but
> the caller has to specify %addr(source), etc. I'd like to avoid that.
>
> I'm looking at changing the source and destination fields to be
> options(*varsize), but there is a strange detail. The V5R2 RPG manual says
> "When OPTIONS(*VARSIZE) is specified, the passed parameter may be shorter
> or longer in length than is defined in the prototype." So it's up to me to
> pass sane fields and a sane length, etc. I'm prepared to do that.
>
> The question is, on options(*varsize) fields, what do I specify as the
> length? The procedure knows to expect data "longer or shorter" (I suppose
> they also mean equal) than whatever I specify for the length. If so, why
> do I have to specify a length at all? I'm thinking about just saying the
> field is 1a options(*varsize). I think that'll be like passing a pointer,
> except the caller doesn't have to do %addr.
>
> Thanks.
> brian.