\n is only converted to newline when it's seen in a string literal by the perl compiler. The compiler doesn't see \n in your example, just $1.

The following makes the compiler see it (by compiling the match everytime one is found):

   warn 'tab' if unescape("\\t")  eq "\t";
   warn 'nl'  if unescape("\\n")  eq "\n";
   warn 'bel' if unescape("\\07") eq "\07";

   sub unescape
   {
      my($s)=@_;

      $s =~ s/(\\[^\d])/ (eval "\"$1\"") || $1 /ge;  # "\t", "\n", etc
      $s =~ s/\\(0\d+)/ eval "chr($1)"         /ge;  # "\07", etc.

      return $s;
   }

[download]

It's more efficient to do the logic yourself:

   my %SLASHED = (
      t => "\t",
      n => "\n",
      r => "\r",
   );

   warn 'tab' if unescape("\\t")  eq "\t";
   warn 'nl'  if unescape("\\n")  eq "\n";
   warn 'bel' if unescape("\\07") eq "\07";

   sub unescape
   {
      my($s)=@_;

      $s =~ s/\\([^\d])/ $SLASHED{$1} || $1 /ge;  # "\t", "\n", etc.
      $s =~ s/\\0(\d+)/ chr(oct($1)) /ge;         # "\07", etc.

      return $s;
   }

[download]

Both solutions are untested.

Update: Tested.

In reply to Re: Unable To Replace Escape Sequences With 1-Char Equivalents by ikegami
in thread Unable To Replace Escape Sequences With 1-Char Equivalents by williams

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