You can profit from the core Scalar::Util's dualvar:

#!/usr/bin/perl
use warnings;
use strict;


{
    package DecHex;
    use Scalar::Util qw(dualvar);

    sub create {
        my $num    = shift;
        my $string = sprintf '%X', $num;
        my $self   = dualvar($num, $string);
    }
}

my $x = DecHex::create 0xFE;
print "$x, ", 0+$x, "\n";
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