Re: [PATCH] First try of null typeset

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

As you might be able to tell, the end of the USA long holiday weekend
has severely reduced my ability to pay attention to this.

On Tue, Dec 1, 2020 at 1:13 AM Felipe Contreras
<felipe.contreras@xxxxxxxxx> wrote:
>
> This achieves most of what Bart Schaefer's version achieves, except no extra hacks are needed, and
> integer and floats are not changed.

Applying the change to integers and floats is one of the reasons I
went in the direction I did.  What constitutes an "extra hack"?

> In my opinion a separate concept of "null" variable will be needed, and should be separate from
> PM_UNSET, since that changes a lot of behavior.

I don't think it's possible to introduce a separate concept of "null"
inside struct param without touching at least all the same places my
branch already did, and probably others.  I would not be unhappy to be
proven incorrect, but PM_UNSET already covers all the corner cases of
what to do when a parameter should be treated as having no value,
because that's how "local" followed by "unset" has always worked.

> Also, I don't think $empty[(i)] should return nothing, so probably paramsubst() would need to be tuned

Agree.  This may be easier than it seems, because (i)/(I) already work
on scalars: { thing="abcde"; print $thing[(I)] } yields 6.  I just ran
out of time to dig further.

> Addtionally, this patch doesn't change the behavior of the private module.

If by this you mean my branch changed something about "private" in a
way that doesn't correspond to the rest of the changes, then I've
overlooked something.