Re: Variable Variable names

[Rich Duzenbury <rduz-midrange@xxxxxxxxxxxxxxxxxxx>]

On Fri, 2005-03-18 at 16:27 +0100, PAPWORTH Paul wrote:
> Does any one know if it is possible in RPG (or any other i_series)
> language to do the following
> 
>  
> 
> Ws_work_zone = %pgmvar(var) 
About fifteen years ago, we needed to write a program where the user
could define rules that edited fields in a set of records.  They needed
to be able to edit against the contents of any field (in a defined list
of several hundred) to see if it was blank, or zero, or matched a list,
or matched one of the other fields in the list.  There were ranges, and
all sorts of requirements.

We thought about various methods, including writing a program generator,
but at the time, it would have been too slow to have the user generate
and compile some kind of program every time they changed the ruleset,
which was frequently.

Finally, someone not really connected to the project said - As soon as
the data is in memory, why not just copy each field into an array
element?  

At first we dismissed the idea out of hand, because it wasn't 'real'
softcoding, which we thought we were after.  However, after a bit of
thought, it became clear that the only 'hardcoding' in the project would
be the bit of code to copy each field into it's array element.

Once that was done, the user could write a rule like "if account type is
111 and end_date is 0, reject the record".  Since we knew account type
was in (say) field 15, and end date was in field (say) 38, we could
easily, at run time, parse the rule(s), and then compare fields(15) with
111 and fields(38) with 0.

HTH

--
Regards,
Rich

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