RE: compile error on %lookup where array is the return value

I guess that means that %lookup is defined to pass by reference.  
The explanation makes sense but it is kind of bad.  This means that below will 
not work, which is pretty common in java, I think.

D string          s            255                       
D getString       pr           255                       
D doSomething     pr                                     
D  piString                    255                       
                                                         
C                   callp     doSomething(getString())   
                                                         
C                   eval      *inlr = *On                
 ********************************************************
P doSomething     B                                      
D                 pi                                     
D piString                     255                       
                                                         
C                   eval      piString = 'x'             
                                                         
P doSomething     E                                      
                                                         
 ********************************************************
P getString       B                                      
D                 pi           255          
                                       
C                   return    string   
                                       
P getString       E                                  
 

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On 
Behalf Of Igor.Beslic@xxxxxxxxxxxx
Sent: Friday, January 13, 2006 4:44 PM
To: RPG programming on the AS400 / iSeries
Subject: RE: compile error on %lookup where array is the return value

It's not strange...
This is principle:
if you pass EXPRESSION to subprocedure sprocedure is receiving address of 
temporary memory location that stores expression result. theoreticly that part 
of memory is not allocated for your PGM so you can't directly change it.

By defining CONST in prototype you garant to caller that received value want be 
changed in subprocedure so system lets you receive that tmp address.
By defining VALUE in prototype system makes copy of result of expr and sends 
new address to subprocedure so you are allowed to do wat you want with received 
value.

Both approachs work if you want your subproc to accept the expressions. 
For more take a look at SourcersGuide at page 50/51 (Chapter3-Power of 
prototyping).

There is no written in documentation that %LOOKUP bif doesn't accept expresions 
in second parm but obviously it doesn't :)

Igor Bešlić, dipl. ing. rač. 
VOLKSBANK d.d.
OJ Informatika
Varšavska 9, 10000 Zagreb
tel: +385 1 4801 895



"Lim Hock-Chai" <Lim.Hock-Chai@xxxxxxxxxxxxxxx> Sent by: 
rpg400-l-bounces@xxxxxxxxxxxx
13.01.2006 22:59
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RPG programming on the AS400 / iSeries <rpg400-l@xxxxxxxxxxxx>


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Subject
RE: compile error on %lookup where array is the return value






You are right, it compiled normally when const/value keyword is present.
Otherwise it failed.  That is strange.



-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Jon Paris
Sent: Friday, January 13, 2006 3:27 PM
To: rpg400-l@xxxxxxxxxxxx
Subject: RE: compile error on %lookup where array is the return value

 >> This works because myLookup always returns 1 AND there is no %lookup
with an expression in the array name parameter.

You forced me to look again Mel - it appears to work because of the
const keyword on the proto for MyLookup.

getArray is a function that returns an array and yet is acceptable as a
parm to MyLookup.  If you remove the const keyword it will not compile.