If you just want \x escapes, you can use a regex: 
#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };

my $string = 'foo\x32\x33\x34bar';
$string =~ s/\\x([0-9a-f][0-9a-f]?)/chr hex $1/gie;
say $string;

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I wouldn't recommend eval.

Update: For full functionality, see String::Interpolate. 

use String::Interpolate qw{ interpolate };
say interpolate($string);

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($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

[download]

In reply to Re: "pack" string read from command line by choroba
in thread "pack" string read from command line by demoralizer

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