I would also recommend localizing $_, because while doesn't do it automatically: 
sub whatever {
  local $_;
  while(<$in>) {
    # do stuff
  }
}

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Even if the loop is not in a sub, localizing $_ can prevent nasty bugs if you decided to wrap the loop in a sub later.

In reply to Re^3: A perverse use of grep by itub
in thread A perverse use of grep by eyepopslikeamosquito

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