Re: CONST Parameter passing, varying and *varsize

"Wilt, Charles" wrote:
> 
> Let me make sure I understand, you said "With const varying
> parameters, with or without *VARSIZE: if the passed varying parameter
> might have a current length that is longer than the prototyped
> parameter, the compiler currently uses a temporary and always assigns
> the passed parameter to the temporary."
> 
> So if I've got a procedure defined like so:
>      d Proc1b          pr
>      d  msgData                   32768a   const varying
> 
> Adding OPTIONS(*VARSIZE) has no effect when passing literals and/or
> string expressions, unless what I'm passing is greater than 32768.

The sentence you quoted was just regarding passing variables defined
with VARYING.  When passing literals and expressions, a temporary is
always used.  With VARYING, the length of the temporary may or may not
be the full length of the prototyped parameter.

I think it's true that OPTIONS(*VARSIZE) makes no difference with CONST
VARYING.  Certainly it's logically true - it's impossible to access the
part of the variable after the current length, at least with valid RPG
coding.  So there's no requirement to pass a parameter any longer than
necessary.  Whether the compiler always takes advantage of that is
another question that I can't answer without spending quite a while
studying the parameter-passing code.

Anyway, trying to optimize compiler temporaries by coding your RPG a
particular way is probably a losing proposition.  Compiler temporaries
are created for more things than just parameter passing.  The compiler
attempts to reuse temporaries as much as possible; by trying to get it
to create a smaller temporary, you might actually cause it to create a
new temporary rather than reuse one of the larger size.