Re: Why you shouldn't be afraid to use VARCHAR in RPGLE

Javier

Have you submitted this as an Idea? IBM do listen to us, and I'm very 
impressed about that.

*Regards*

*Vern Hamberg*

IBM Champion 2025 <cid:[email protected]> CAAC 
(COMMON Americas Advisory Council) IBM Influencer 2023


On 12/11/2025 8:14 AM, Javier Sanchez wrote:
> Thanks Barbara.  Nothing better than explanations coming from the creators
> of the compiler.  Of course you guys know what all that means and your
> contributions will always be appreciated.
>
> BTW, I have wondered a lot why you guys have not yet implemented the C-like
> expression as:
> boolVal = (a = b ? 0: 1);
> This is not only necessary for modern RPG but it should have been provided
> long time ago! :-)
> JS
>
> El mié, 10 dic 2025 a las 22:04, Barbara Morris (<[email protected]>)
> escribió:
>
>> On 2025-12-10 12:25 p.m., James H. H. Lampert via RPG400-L wrote:
>>> On 12/10/25 4:06 AM, Infodorado InfoDorado via RPG400-L wrote:
>>>> The RPG compiler is a single-pass compiler
>>> No, it can't be pure single-pass. If it were, then a program in which a
>>> variable is NOT defined in a D-spec, nor in the first C-spec in which it
>>> appears, would not compile, much less run. And it's trivially simple to
>>> construct an example of this (it took me about 2 minutes), and it
>>> compiles and runs just fine. I'd quote the source here, but it would
>>> likely be mangled beyond recognition.
>>>
>> It's a single pass through the source but it gathers information that it
>> can use multiple times.
>>
>> The compiler usually allows forward-referencing, so you can code LIKE(x)
>> where x is defined later.
>>
>> But for free-form definitions, the compiler requires the parameter for
>> the data-type keywords to be defined before the keyword is seen.
>>
>>      dcl-s x char(con1);  // bad, con1 not defined yet
>>      dcl-c con1 5;
>>      dcl-s y char(con1);  // ok, con1 is defined
>>
>> Where it becomes extra fun is when you have a data structure that LOOKS
>> defined.
>>
>>      dcl-ds ds1;
>>         subf char(10);
>>      end-ds;
>>      dcl-s x char(%size(ds1));  // %size(ds1) is not defined. WHAT???
>>
>> RPG allows you to define the length of a data structure later, either
>> due to being on an I spec, possible an externally-described I spec, or
>> on a C spec.
>>
>>        C            MOVE    *blanks       ds1        50
>>
>> Almost certainly wrong columns, but you get what I mean. I'm defining
>> DS1 to have a length of 50 here, not the length of 10 that it looked
>> like it should have. Shenanigans? Yep, but upward-compatible R Us.
>>
>> We have a H-spec/CTL-OPT keyword for that: DLCOPT(*NOCHGDSLEN). With
>> that keyword, the compiler doesn't allow you to change the length of the
>> data structure like that, so it's considered defined as soon as all the
>> subfields are defined.
>>
>> --
>> Barbara
>>
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