RE: Problem with non QUALIFIED DS

-----Message d'origine-----
De : rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] De la part de Vern Hamberg
Envoyé : jeudi 24 septembre 2009 15:15
À : RPG programming on the IBM i / System i
Objet : Re: Problem with non QUALIFIED DS

David

A dummy pointer is often used - before v6r1 - to declare a
template variable or structure. It uses no memory, but it can
be used to define other data structures with LIKEDS - a very
handy thing. The basing pointer is also useful for data type
definitions similar to what C/C++ has. You then use the LIKE
keyword in your code.

Vern

David FOXWELL wrote:

Thanks Birgitta, I shall keep your example for future

reference. I find it a little hard reading pulling in 1
prototype at a time. Then again, the prototypes that caused
my problem were prototypes I didn't even need!

I have another question concerning the dummy pointer. It

seems I am the only one here that never declares that
pointer. It seems to me that if you declare it, you intend to
use it, and all the data structures based on it can then be
used. Is it unwise to declare the pointer for template based fields?

-----Message d'origine-----
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] De la part de

Birgitta Hauser

Hi,

I'm also using a data structure of the field reference

file and data

structures that are passed as parameters in my prototypes.
There is almost no field within my application that is not defined
with like or likeDS. Exceptions maybe indexes for looping through
arrays.
The data structures itself are (most times) in separate

copy members

and surrounded with compiler directives. These copy members are
included within my prototypes (nested copy members).
Also the names of the references start with REF (except my field
reference file which is simply named FldRef).
In this way I never have any problems except I have to use

qualified

data structures.

All prototypes are located in a source file named

QPROLESRC with the

same name as the source of the module or program All Copy

members for

data structures and Reference fields are located in a source file
named QCPYLESRC.

For example
Copy members for references
/If Not Defined (FldRef)
/Define (FldRef)
D FldRef E DS ExtName(DWFldRef)

Based(DummyPtr)

/EndIf

/If Not Defined (RefDSMyFile)
/Define (RefDSMyFile)
D RefDSMyFile E DS ExtName(MyFile) Based(DummyPtr)
/Endif

Prototype 1
/Include QCPYLESRC,FldRef
/Include QCPYLESRC,MyFile

/If Not Defined (MyProc)
/Define MyProc
D MyProc PR
D Parm1 Like(FldRef.MyField1) const
D Parm2 LikeDS(RefDSMyFile) Const
/Endif

/If Not Defined MyFct
/Define MyFct
D MyFkt PR Like(FldRef.MyFieldY)
D Parm1 Like(FldRef.MyFieldx) Const
/EndIf

Prototype 2
/Include QCPYLESRC,FldRef
/Include QCPYLESRC,MyFile2

/If Not Defined (MyProc2)
/Define MyProc2
D MyProc2 PR
D Parm1 Like(FldRef.MyFieldA) const
D Parm2 LikeDS(RefDSMyFile2) Const
/Endif

Program/Module

D/Include QPROLESRC,Proto1
D/Include QPROLESRC,Proto2

Mit freundlichen Grüßen / Best regards

Birgitta Hauser

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