Devel::Peek::Dumpの信用できるところと信用出来ないところ

Devel::Peek::Dumpは同じアドレス空間の変数に対して、IV/NV/PVとかここの要素は更新しないっぽい。 (最後のundefをdumpした時にもIV/NVが存在しているし、SV=XXの部分も更新されない)

#!/usr/bin/env perl
use 5.10.0;
use strict;
use warnings;
use Devel::Peek;

Test::Devel::dump(2);
Test::Devel::dump(1.1);
Test::Devel::dump(undef);
Test::Devel::dump('a');
Test::Devel::dump(undef);


package Test::Devel;
sub dump {
    my $value = shift;
    Devel::Peek::Dump($value);
}

SV = IV(0x7f82d304e458) at 0x7f82d304e468
  REFCNT = 1
  FLAGS = (PADMY,IOK,pIOK)
  IV = 2
SV = PVNV(0x7f82d3004a30) at 0x7f82d304e468
  REFCNT = 1
  FLAGS = (PADMY,NOK,pNOK)
  IV = 2
  NV = 1.1
  PV = 0
SV = PVNV(0x7f82d3004a30) at 0x7f82d304e468
  REFCNT = 1
  FLAGS = (PADMY)
  IV = 2
  NV = 1.1
  PV = 0
SV = PVNV(0x7f82d3004a30) at 0x7f82d304e468
  REFCNT = 1
  FLAGS = (PADMY,POK,IsCOW,pPOK)
  IV = 2
  NV = 1.1
  PV = 0x7f82d2c0f0f0 "a"\0
  CUR = 1
  LEN = 16
  COW_REFCNT = 1
SV = PVNV(0x7f82d3004a30) at 0x7f82d304e468
  REFCNT = 1
  FLAGS = (PADMY)
  IV = 2
  NV = 1.1
  PV = 0

ちなみに、Cloneとか使ってこうやればIV/NVあたりは初期化される。 が、typeは更新されない。

#!/usr/bin/env perl
use 5.10.0;
use strict;
use warnings;
use Devel::Peek;
use Clone qw(clone);

Test::Devel::dump(2);
Test::Devel::dump(1.1);
Test::Devel::dump(undef);
Test::Devel::dump('a');
Test::Devel::dump(undef);


package Test::Devel;
sub dump {
    my $value = shift;
    Devel::Peek::Dump(Clone::clone($value));
}

SV = IV(0x7fdcea805dd8) at 0x7fdcea805de8
  REFCNT = 1
  FLAGS = (TEMP,IOK,pIOK)
  IV = 2
SV = PVNV(0x7fdcea804a50) at 0x7fdcea805c38
  REFCNT = 1
  FLAGS = (TEMP,NOK,pNOK)
  IV = 0
  NV = 1.1
  PV = 0
SV = PVNV(0x7fdcea804a50) at 0x7fdcea805de8
  REFCNT = 1
  FLAGS = (TEMP)
  IV = 0
  NV = 0
  PV = 0
SV = PVNV(0x7fdcea804a50) at 0x7fdcea805c38
  REFCNT = 1
  FLAGS = (TEMP,POK,pPOK)
  IV = 0
  NV = 0
  PV = 0x7fdcea4160d0 "a"\0
  CUR = 1
  LEN = 16
SV = PVNV(0x7fdcea804a50) at 0x7fdcea805de8
  REFCNT = 1
  FLAGS = (TEMP)
  IV = 0
  NV = 0
  PV = 0

ってことで、素直にIV/SVとか見たいときは、 FLAGSを見るとか、 以下の様にB::svref_2objectで作ったオブジェクトの中からFLAGSを持って来る必要があるっぽい

B::svref_2object(\$value)->FLAGS;

そして普通に書いてあった！！ https://metacpan.org/pod/Devel::Peek#A-simple-scalar-string