Re: VARLEN dds field in RPG-IV -- RPG400-L

GA,

To check to see if the length was not set by the compiler would be as 
difficult as checking to see if this was a divide by zero:
/free
 z=x/y;
/end-free
y could have been set in the program, could have been passed in as a 
parameter, could have been read in from a file.  Same story with the 
length.

Would you be happy with a warning message
RNF....  The MOVE opcode is about to be deprecated.  Find a better 
alternative

:-)

Rob Berendt
-- 
"They that can give up essential liberty to obtain a little temporary 
safety deserve neither liberty nor safety." 
Benjamin Franklin 





G Armour <garmour400r@xxxxxxxxx>
Sent by: rpg400-l-bounces@xxxxxxxxxxxx
08/28/2003 12:12 PM
Please respond to RPG programming on the AS400 / iSeries
 
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        Subject:        Re: VARLEN dds field in RPG-IV


Excellent explanation, Hans!  And right along the lines that I was 
thinking of.

Still, I wonder (but don't doubt your word) why the compiler can't "see" 
that the
field-length prefix isn't being set.  Maybe easier, if it isn't even being
referenced? 

I told my colleagues not to lose too many brain cells on this; just use 
the EVAL and
life will be good.

Thanks again!
GA

--- Hans Boldt <boldt@xxxxxxxxxx> wrote:
<snip> 
> I think this is largely a case of "working as designed".
> 
> To summarise the rules: When using varying length variables within 
> the traditional fixed-form calcs (not the expression calcs), a 
> varying length variable works the same as a fixed length field 
> defined with the current length. That is, if the current length of a 
> char varying field is 10 (regardless of the declared maximum 
> length), then the operation works the same as is the field were 
> fixed length 10 chars.
> 
> Of course, if the current length is 0, then there's not really an 
> analogue in the fixed length case. But we're not going to make any 
> change to the compiler that might possibly regress users, and so 
> that behavior ain't gonna change.
> 
> Why this way? The rules for char result on the old fixed-form calcs 
> get in the way of meaningful rules for varying length variables. For 
> example, for many fixed-form opcodes, char results are generally 
> unpadded and right adjusted. Just how exactly do you right-adjust a 
> value in a varying length result? We settled on the current rules 
> for fixed-form calcs since you get the results you generally expect 
> in the expression calcs anyways, and we wanted to keep the rules 
> consistent for all fixed-form calcs.
> 
> Regarding a warning (sev 10) message, I can't think of any warning 
> that would specifically warn about this situation. The compiler 
> generally can't know that a varying length variable never gets its 
> length set.
> 
> Cheers! Hans


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