Re: Data structure overlay *next failure

I thought you had accidentally left the size off of XWrkC below. I didn't
get that a sub-field could be automatically sized by the fields overlaying
it. That will help with a number of things I work on, in addition to the
immediate issue I was having, so thank you for pointing out that little
tip.




From: Jon Paris <jon.paris@xxxxxxxxxxxxxx>
To: "RPG programming on the IBM i \(AS/400 and iSeries\)"
<rpg400-l@xxxxxxxxxxxx>
Date: 06/19/2013 09:56 AM
Subject: Re: Data structure overlay *next failure
Sent by: rpg400-l-bounces@xxxxxxxxxxxx



Why are you using *next at all on the early fields? It has no effect and
(as you have seen) can create confusion you. In fact it confuses things so
much I'm not absolutely sure what you area trying to do.

This:

D ParmDS DS INZ
D XEnd6 overlay(ParmDS)
D XWeeks overlay(ParmDS:*next)
D xFac overlay(ParmDS:*next)

And this:

D ParmDS DS INZ
D XEnd6
D XWeeks
D xFac

Are identical in effect.

If you are trying to create an array over a set of database fields then use
a group field like so:

D XwrkC
D XWrkC1 overlay(XwrkC)
D XWrkC2 overlay(XwrkC:*next)
D XWrkC3 overlay(XwrkC:*next)
D XWrkC4 overlay(XwrkC:*next)
D XWrkC5 overlay(XwrkC:*next)
D XWrkC6 overlay(XwrkC:*next)
D XWrkCA Like(xWrkC1) Dim(6)
D overlay(XwrkC)

This is using *Next the way it should be - to redefine something.

I've written a shoe article on this topic - check out
http://www.ibmsystemsmag.com/ibmi/developer/general/D-spec-Discoveries/



On 2013-06-19, at 9:17 AM, darren@xxxxxxxxx wrote:

I'm having an issue creating arrarys over fields in a data structure. I
have something like the following, but the *next function doesn't work

with

the arrays. They seem to get their own memory, rather than being

overlaid

on the XWrkC* fields. I've seen lots of overlay examples, but I don't

see

them specify the actual data structure name in the overlay *next command,
so I'm wondering if there is some restriction I haven't seen yet, where

you

aren't supposed to overlay on the data structure itself, but only on the
subfields. In this case, the fields are actually display file fields,

but

I've seen this behavior with independently declared fields as well.



D ParmDS DS INZ
D XEnd6 overlay(ParmDS)
D XWeeks overlay(ParmDS:*next)
D xFac overlay(ParmDS:*next)
D XBuyC overlay(ParmDS:*next)
D XPlnC overlay(ParmDS:*next)
D XPVnd overlay(ParmDS:*next)
D XDept overlay(ParmDS:*next)
D XITYP overlay(ParmDS:*next)
D XWrkC1
D XWrkC2
D XWrkC3
D XWrkC4
D XWrkC5
D XWrkC6
D XWrkCA Like(xWrkC1) Dim(6)
D overlay(ParmDS:*next)
D xItem1
D xItem2
D xItem3
D xItem4
D xItem5
D xItem6
D xItemA Like(xItem1) Dim(6)
D overlay(ParmDS:*next)

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Jon Paris

www.partner400.com
www.SystemiDeveloper.com




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