Re: Data structure overlay *next failure

[Jon Paris <jon.paris@xxxxxxxxxxxxxx>]

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

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