Thanks Rob, that's essentially the sort of thing I currently need to do, but it requires knowing the exact structure to be dumped and walking it myself. I also want to distinguish between GMP objects and simple integers - particularly to spot when something that should be GMP is not or v.v. - so I'd end up needing to write most of Data::Dumper myself. I had hoped somebody would already have done that for me (and that someone here would have used it).

My CPAN-fu is minimal, but of the 2,520 matches on metacpan for 'dump', a quick scan of the first 100 threw up some maybes such as Data::Printer (which cares mostly about coloured output) and Data::Dump::Streamer (which cares mostly about structure recreatability via eval). I also spotted a cross-reference to Data::Rmap, which might offer a sane way to roll my own. I'll try some of those and see what I get.

I also want to distinguish between GMP objects and simple integers

Yes - inside my own gmp-based modules I often want to know about such things.
I normally use XS or Inline::C subroutines for this.

In pure perl code, as you may already be well aware, the ref() function will go a long way to providing useful information about references and module objects.

use warnings;
use Math::BigInt;
use Math::GMP;

my $v = 9;
my %h = (foo => $v);

for (\%h, [$v], \$v, Math::GMP->new($v), Math::BigInt->new($v), $v) {
  ref($_) ? print ref($_), "\n"
          : print "Not a reference\n";
}

__END__

Outputs:

HASH
ARRAY
SCALAR
Math::GMP
Math::BigInt
not a reference
[download]

You can also use the B module instead of XS/Inline::C to determine whether a scalar is an IV or an NV or a PV or a combination thereof.

If you want more info on any of these aspects, just ask.
(I don't want to annoy you by banging on with stuff that you already know (or stuff that you're not particularly interested in).

Cheers,
Rob

Thanks Rob, I am indeed pretty conversant with that stuff. The aim here is to avoid writing my own dumping module just to get around the lack of a single feature in the standard one - there is a forest of them already on CPAN, it seems very likely there would already be one ideal for my needs (or needing at most minor topiary).

See also my update on the root post where I describe what I'm currently experimenting with via Data::Printer: that is working at least well enough to let me get further with the code I was originally trying to write.