Re: Idea submitted: Built in function to subset an array using a procedure to filter

On Mon, Nov 10, 2025 at 1:14 PM Mark Waterbury via RPG400-L <
[email protected]> wrote:

> You might also consider creating a temporary table in Db2, and then load
> the entire array into the temp table, and then you can use the full power
> of SQL to query the temp table, and create a "results set" containing only
> the subset that you are interested in.   And, when done, you can just DROP
> the temp table.
>
> I think this should be much easier and more straight-forward than your
> proposed "enhancement" to RPG IV.
>

DB2 adds a WHOLE lot of overhead for something that should be able to be
done in memory.

Alternatively, some kind of utility like qsort that takes two arrays and a
procptr to filter the entries

Hmmm ... I wonder how hard that kind of thing would be to write in RPG?

You've given me an idea.

david


> All the best,
>
> Mark S. Waterbury
>
>
> On Tuesday, November 4, 2025 at 01:36:03 PM EST, David Gibbs via RPG400-L <
> [email protected]> wrote:
>
>
>
>
>
> So I submitted a enhancement request to the Ideas site to add a built in
> function to subset an array using a procedure to determine if the array
> element should be included.
>
> https://ibm-power-systems.ideas.ibm.com/ideas/IBMI-I-4699
>
> Create a new built in function to subset an array using a procedure to
> filter.
>
> Similar to the %SUBARR function, but allow a procedure to be specified to
> determine if the array entry should be included in the result.
>
> Something like ...
>
> dcl-ds arraySpec_t qualified template;
>   subField1 char(10);
>   subField2 char(10);
> end-ds;
>
> dcl-ds newArray likeds(arraySpec_t);
> dcl-ds oldArray likeds(arraySpec_t);
> .
> .
> newArray = %FILTERARR(oldArray:1:%elem(oldArray):filterProc);
> .
> .
> .
> dcl-proc filterProc;
>   dcl-pi *n ind;
>     entry likeds(arraySpec_t) const;
>   end-pi;
>   return entry.subField1 = 'xyz';
> end-proc;
>
>
> Any comments on this?
>
> david
>
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-- 
IBM i on Power Systems: For when you can't afford to be out of business!

I'm riding in the American Diabetes Association's Tour de Cure to raise
money for diabetes research, education, advocacy, and awareness.  You can
make a tax-deductible donation to my ride by visiting
https://mideml.diabetessucks.net.

I may have diabetes, but diabetes doesn't have me!
-- 
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