Apparently, this special variable is only a string in perl 5.10, even though the documentation seems to suggest that it be a floating point number. If you use $]+0 in your example, it'll work (which is kind of strange because ordinary hash keys are converted to strings anyway, but in this case I think we are dealing with a tied hash).

% perl5.8.8 -we 'use Devel::Peek; Dump $]' 
SV = PVNV(0x9f664d0) at 0x9f63ed0            
  REFCNT = 1
  FLAGS = (NOK,POK,READONLY,pNOK,pPOK)
  IV = 0
  NV = 5.008008                       #  <-- in 5.8 it was a number
  PV = 0x9f7d250 "5.008008"\0
  CUR = 8
  LEN = 12

% perl5.10.0 -we 'use Devel::Peek; Dump $]'  
SV = PV(0x9457198) at 0x946a610
  REFCNT = 1
  FLAGS = (POK,READONLY,pPOK)
  PV = 0x945e538 "5.010000"\0
  CUR = 8
  LEN = 12

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In reply to Re: Problem with accessing hash Module::CoreList::version with $] by betterworld
in thread Problem with accessing hash Module::CoreList::version with $] by XooR

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