Re: What's in a Reference?

[almut]

use Devel::Peek;

my $x = 42;
my $y = \$x;

Dump $y;

__END__
SV = RV(0x63fde0) at 0x604fc0
  REFCNT = 1
  FLAGS = (PADBUSY,PADMY,ROK)
  RV = 0x604fa0                     <---
  SV = IV(0x62de60) at 0x604fa0
    REFCNT = 2
    FLAGS = (PADBUSY,PADMY,IOK,pIOK)
    IV = 42

I'd call it an address.  But in contrast to a C pointer, a Perl reference also maintains other info, and doesn't allow you to directly fiddle with the address.

(Note that the SV ... at 0x604fa0 is not part of the reference itself — Devel::Peek just dumps the referenced target, too, for convenience.)

[ikegami]

Different question than last night. He's asking for the relation between the following and $y.

SV = RV(0x63fde0) at 0x604fc0
  REFCNT = 1
  FLAGS = (PADBUSY,PADMY,ROK)
  RV = 0x604fa0
  SV = IV(0x62de60) at 0x604fa0
    REFCNT = 2
    FLAGS = (PADBUSY,PADMY,IOK,pIOK)
    IV = 42                         <---

[almut]

Well, I don't know what was being discussed last night, but I understand the question kind of like this:

"A C reference/pointer holds an address, what would you call the analogous thing which a Perl reference holds?"  As the subject says: "What's in a reference?"

Anyhow, only Xiong call tell what he really meant.

[ikegami]

Ah right, I thought he asked

$3 = 3;
$2 = \$3;
3 is the ________ of $2

instead of

$3 = 42;
$2 = \$3;
3 is the ________ of $2

There's not even a 3 in his setup.