use Devel::Peek;
use Readonly;

Readonly my $C1 => 0x0004;
Readonly my $C2 => 0x0008;
                         
Dump($C1);           # before first evaluation
#Dump($C2);

my @x = ($C1, $C2);  # somehow access variables

my $C3 = $C1 | $C2;

Dump($C1);           # after first evaluation
#Dump($C2);

print "\nValue of C3 = ", $C3, "\n";

##</code><code>##

SV = PVMG(0x69b788) at 0x65eb00
  REFCNT = 1
  FLAGS = (PADBUSY,PADMY,GMG,SMG,RMG)
  IV = 0
  NV = 0
  PV = 0
  MAGIC = 0x6e8ff0
    MG_VIRTUAL = &PL_vtbl_packelem
    MG_TYPE = PERL_MAGIC_tiedscalar(q)
    MG_FLAGS = 0x02
      REFCOUNTED
    MG_OBJ = 0x63c430
    SV = RV(0x676bd8) at 0x63c430
      REFCNT = 1
      FLAGS = (ROK)
      RV = 0x6b87d0
      SV = PVMG(0x69b750) at 0x6b87d0
        REFCNT = 1
        FLAGS = (PADBUSY,PADMY,OBJECT,IOK,POK,pIOK,pPOK)
        IV = 4
        NV = 0
        PV = 0x7083b0 "4"\0
        CUR = 1
        LEN = 8
        STASH = 0x6b8990        "Readonly::Scalar"
SV = PVMG(0x69b788) at 0x65eb00
  REFCNT = 1
  FLAGS = (PADBUSY,PADMY,GMG,SMG,RMG,pIOK,pPOK)    # <---
  IV = 4
  NV = 0
  PV = 0x6b4c50 "4"\0
  CUR = 1
  LEN = 8
  MAGIC = 0x6e8ff0
    MG_VIRTUAL = &PL_vtbl_packelem
    MG_TYPE = PERL_MAGIC_tiedscalar(q)
    MG_FLAGS = 0x02
      REFCOUNTED
    MG_OBJ = 0x63c430
    SV = RV(0x676bd8) at 0x63c430
      REFCNT = 1
      FLAGS = (ROK)
      RV = 0x6b87d0
      SV = PVMG(0x69b750) at 0x6b87d0
        REFCNT = 1
        FLAGS = (PADBUSY,PADMY,OBJECT,IOK,POK,pIOK,pPOK)
        IV = 4
        NV = 0
        PV = 0x7083b0 "4"\0
        CUR = 1
        LEN = 8
        STASH = 0x6b8990        "Readonly::Scalar"

Value of C3 = <