Dump before:
SV = PV(0xf0c44) at 0xfe99c
  REFCNT = 1
  FLAGS = (POK,pPOK)
  PV = 0xf7560 "some text here "\0
  CUR = 15
  LEN = 16

Dump inside trim():
$_[0] (this one is infact a 'synonym' to the actual variable; not it's copy :-) :
SV = PV(0xf0c44) at 0xfe99c
  REFCNT = 1
  FLAGS = (POK,pPOK)
  PV = 0xf7560 "some text here "\0
  CUR = 15
  LEN = 16

$s (this is a copy of the 1-st argument:
SV = PV(0xf0c98) at 0xfe9c0
  REFCNT = 1
  FLAGS = (PADBUSY,PADMY,POK,pPOK)
  PV = 0xf7540 "some text here "\0
  CUR = 15
  LEN = 16

Dump inside bar(\$):
$_[0]:
SV = RV(0x11581c) at 0xf096c
  REFCNT = 1
  FLAGS = (ROK)
  RV = 0xfe99c
  SV = PV(0xf0c44) at 0xfe99c
    REFCNT = 3
    FLAGS = (POK,pPOK)
    PV = 0xf7560 "some text here "\0
    CUR = 15
    LEN = 16

$s (this is a copy of the 1-st argument, which is nothing more but a reference..):
SV = RV(0x115828) at 0x1164b0
  REFCNT = 1
  FLAGS = (PADBUSY,PADMY,ROK)
  RV = 0xfe99c
  SV = PV(0xf0c44) at 0xfe99c
    REFCNT = 3
    FLAGS = (POK,pPOK)
    PV = 0xf7560 "some text here "\0
    CUR = 15
    LEN = 16

Dump after:
SV = PV(0xf0c44) at 0xfe99c
  REFCNT = 1
  FLAGS = (POK,pPOK)
  PV = 0xf7560 "some text here "\0
  CUR = 15
  LEN = 16