Re: Could RPG become quasi-immune to level checks (was: Are level checks still useful?)

[Alan Campin <alan0307d@xxxxxxxxx>]

I have been thinking the same thing for years but the whole issue is really
mute now. Programs should be coded with SQL. All these issues vanish and we
get so much more.


On Thu, Nov 1, 2012 at 10:43 AM, Jeff Crosby <jlcrosby@xxxxxxxxxxxxxxxx>wrote:

> > The reason you don't have level checks in PHP (and similar environments)
> > is because they don't have hard-coded from/to positions in fields in the
> > record.  When you compile an RPG program, the compiler reads the
> > external definition, and hard-codes the from/to positions of fields in
> > the record into the program.  You have to recompile for it to update
> > these -- and therefore, level checks are an important safeguard. Without
> > them, if the file changes, you'll end up reading (or worse, writing)
> > incorrect data at incorrect places in the record, causing a big huge
> mess.
> >
>
> Scott's post got me thinking.
>
> Theoretically, could RPG be enhanced such that the from/to positions are
> _not_ hard-coded at compile time?  Instead, based on field name (whether
> renamed or not), the from/to positions would be established at run time.
>  If so, one would also have to code updates properly, i.e., either  via
> "Update RecordName %Fields(blah:blah:blah);" or making sure the O specs
> have no end position.
>
> Even though I have absolutely no experience whatsoever in compiler writing
> (and don't want any), I can imagine how this would fundamentally affect the
> compiler.
>
>
> --
> Jeff Crosby
> VP Information Systems
> UniPro FoodService/Dilgard
> P.O. Box 13369
> Ft. Wayne, IN 46868-3369
> 260-422-7531
> www.dilgardfoods.com
>
> The opinions expressed are my own and not necessarily the opinion of my
> company.  Unless I say so.
> --
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