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

[Bryce Martin <BMartin@xxxxxxxxxxxx>]

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
> Please respond to
> RPG programming on the IBM i / System i <rpg400-l@xxxxxxxxxxxx>
>
>
> To
> "RPG programming on the IBM i / System i" <rpg400-l@xxxxxxxxxxxx>
> cc
>
> 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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