Re: BUG #1956: Plpgsql top-level DECLARE does not share scope

On Thu, Oct 13, 2005 at 01:30:56PM -0400, Tom Lane wrote:
> "Jim C. Nasby" <jnasby@pervasive.com> writes:
> > Based on all that, I would certainly be in favor of throwing a warning
> > if you over-define something, since 99% of the time it's a mistake. Is
> > that possible with the current checking we do at compile time?
>
> Without having looked at the code, I imagine the problem is that we
> can't tell this situation from an ordinary nested DECLARE block,
> that is
>
>     declare x int;
>     begin
>         ...
>         declare x float;
>         begin
>             ...
>
> The above is legal code and I don't think we should throw a warning for
> it.
>
> Basically, DECLARE introduces a new name scope that wouldn't be there
> if you didn't say DECLARE.  Without some bizarre reinterpretation of the
> meaning of a DECLARE at the start of a function, variables automatically
> created by plpgsql are going to be in an outer scope surrounding that of
> the first DECLARE.

Yeah, I agree that in the legitimate case it makes much less sense to
throw an error.

Are blocks that aren't explicitely labled assigned a machine-generated
label? If so then it should be possible to tell if something is in the
outer-most block or if it's part of the function declaration itself. But
I have no idea how difficult it would be to do that.

Another possibility is tracking what level sub-block something is in,
and using that to determine if the top-most declare in a function is
over-writing something.
--
Jim C. Nasby, Sr. Engineering Consultant      jnasby@pervasive.com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461