RE: Trying to get the size of a Datastructure throughthe pointer? Possible? Not having good luck with it...

Bryce,

If you have control over the data structure format you could add a size field to the front of the data structure initialized using %Size. Then the pointer would always address a size field using your own convention. Some of the API data structures are formatted this way to start with a size field.

Paul

Principal Programmer Analyst
IS Supply Chain/Replenishment

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Bryce Martin
Sent: Friday, November 19, 2010 1:45 PM
To: RPG programming on the IBM i / System i
Subject: RE: Trying to get the size of a Datastructure throughthe pointer? Possible? Not having good luck with it...

Yeah, I get all that. I was just running some wild ideas through my head
about code generalization that would only be possible if I could do
certain things. Just pie in the sky thinking... I'll move on to more
concrete stuff the rest of the day =^)


Thanks
Bryce Martin
Programmer/Analyst I
570-546-4777



"Dennis Lovelady" <iseries@xxxxxxxxxxxx>
Sent by: rpg400-l-bounces@xxxxxxxxxxxx
11/19/2010 01:06 PM
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RPG programming on the IBM i / System i <rpg400-l@xxxxxxxxxxxx>


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Subject
RE: Trying to get the size of a Datastructure through the pointer?
Possible? Not having good luck with it...






I you're passing a pointer, I believe OPDESC would only pass the
attributes
of the pointer. The issue is that a pointer addresses some location in
memory that contains arbitrary data. The type of that data, and how it
gets
processed, is a matter of interpretation. The pointer certainly doesn't
know (at least not in RPG). Heck, it might even be pointing to some
multi-use area whose "description" is based upon other conditions. It'd
be
unreasonable to expect the compiler to sort that out, let alone the
runtime.

Dennis Lovelady
http://www.linkedin.com/in/dennislovelady
--
Nothing is foolproof to a sufficiently talented fool.

I didn't think it was possible, but couldn't hurt asking :)


Thanks
Bryce Martin
Programmer/Analyst I
570-546-4777



Rory Hewitt <rory.hewitt@xxxxxxxxx>
Sent by: rpg400-l-bounces@xxxxxxxxxxxx
11/19/2010 12:02 PM
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RPG programming on the IBM i / System i <rpg400-l@xxxxxxxxxxxx>


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Subject
Re: Trying to get the size of a Datastructure through the pointer?
Possible? Not having good luck with it...






Bryce,

Quick answer is no, you can't.

It *may* be possible to determine how much memory the system allocated
for
a
basing pointer using an MI instruction, but that allocated memory would
always be in increments of 16 bytes (at a minimum), so even if you
could
get
that value, all you'd really be able to figure out is that your
data-structure is no larger than that size.

Rory

On Fri, Nov 19, 2010 at 8:17 AM, Bryce Martin <BMartin@xxxxxxxxxxxx>
wrote:

I won't go into a lot of details behind this, I have a very specific
question....

The following DataStructure
D MasterList_T...
D DS qualified based(TEMPLATE)
D Line...
D 3s 0
D Item...
D 15a
D Quantity...
D 11s 3
D LeadTimeDate...
D 8s 0

When I do a %size(MasterList_T) I get 37 bytes. When I do

%size(TEMPLATE)

I get 16. Makes sense, its how big the memory address is. No

problem.
My

question, is it possible to get the size of MasterList_T from its

basing

pointer? Is there a bif or something that will let me get it?

Thanks
Bryce Martin
Programmer/Analyst I
570-546-4777

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