Re: Procedure PR/PI question

I agree with you if the receiving program had it coded as CONST but how
much control do we have over that? Almost all the programs that we call to
are legacy programs that somebody wrote 20 years ago and are still being
used. On my new job, I am having to call programs written years ago all the
time because that is what is out there. I cannot go into that old code and
change it to use CONST parameters. Like I said, if I am smart I will make
sure I make a local copy of any parameter that is passed by CONST and pass
that to a procedure but if I am not thinking that day I might screw up and
not do that.


On Mon, Apr 29, 2013 at 4:29 PM, Jon Paris <jon.paris@xxxxxxxxxxxxxx> wrote:

On Mon, 29 Apr 2013, at 14:16:35, Rory Hewitt <rory.hewitt@xxxxxxxxx>
wrote:

CONST means I will try to keep you from changing it but there are plenty

of

ways to change the variable inside the procedure and have the calling
variable to be changed.

I agree that it is possible Rory, but not as easy as you are making it
sound.

These include passing as a parameter to a program inside the procedure,

If the receiving program had a PI and the parm was defined as CONST this
is not permitted. The compiler will not permit the programmer to pass a
CONST parm in any way other that as another CONST or VALUE parm.

getting a pointer to it,

As above - not permitted.

putting in a data structure.

Nope - that would be a copy of the data.

The compiler may try to prevent you from changing but it is easy enough

to

change which could result in some really nasty bugs.

The only "easy" way is if the receiving program does not have a PI
defining the parm as CONST. Anything else requires more work.


Jon Paris

www.partner400.com
www.SystemiDeveloper.com




--
This is the RPG programming on the IBM i (AS/400 and iSeries) (RPG400-L)
mailing list
To post a message email: RPG400-L@xxxxxxxxxxxx
To subscribe, unsubscribe, or change list options,
visit: http://lists.midrange.com/mailman/listinfo/rpg400-l
or email: RPG400-L-request@xxxxxxxxxxxx
Before posting, please take a moment to review the archives
at http://archive.midrange.com/rpg400-l.