use Storable;
use MIME::Base64;
use Data::Dumper;

eval {
 die encode_base64(freeze({errorcode => 12, errormess => 'you have died'}));
};
print "error caught: ".Dumper(thaw(decode_base64($@))) if $@;

##</code><code>##

use Data::Dumper;

eval {
 die {errorcode => 12, errormess => 'you have died'};
};
print "error caught: ".Dumper($@) if $@;
# or even better
eval {
 die bless {errorcode => 12, errormess => 'you have died'} => 'My::Exception';
};
print "error caught2: ".$@->{errormess}."\n" if $@ and ref($@) eq 'My::Exception';  

##</code><code>##

use Storable qw/freeze thaw/;
use MIME::Base64;
use Data::Dumper;
use Benchmark qw/:all/;

use strict;
use warnings;

sub die_bliako_way {
  die encode_base64(freeze({errorcode => 12, errormsg => 'you have died'}));
}
sub die_common_sense {
  die {errorcode => 12, errormsg => 'you have died'};
}
sub die_common_sense_blessed {
  die bless {errorcode => 12, errormsg => 'you have died'} => 'My::Exception';
}
sub no_die {
  return {errorcode => 12, errormsg => 'you have died'};
}
timethese(10_000_000, {
  'die_bliako_way' => sub {
    eval { die_bliako_way };
    if( $@ && exists(thaw(decode_base64($@))->{errorcode}) ){  }
  },
  'die_common_sense' => sub {
    eval { die_common_sense };
    if( $@ && exists($@->{errorcode}) ){  }
  },
  'no_die' => sub {
    my $ret = no_die();
    if( exists $ret->{errorcode} ){  }
  }
});

##</code><code>##

Benchmark: timing 10000000 iterations of die_bliako_way, die_common_sense, die_common_sense_blessed, no_die...
die_bliako_way: 56 wallclock secs (55.04 usr +  0.01 sys = 55.05 CPU) @ 181653.04/s (n=10000000)
die_common_sense:  5 wallclock secs ( 5.25 usr +  0.00 sys =  5.25 CPU) @ 1904761.90/s (n=10000000)
die_common_sense_blessed:  5 wallclock secs ( 5.36 usr +  0.00 sys =  5.36 CPU) @ 1865671.64/s (n=10000000)
    no_die:  5 wallclock secs ( 3.77 usr +  0.00 sys =  3.77 CPU) @ 2652519.89/s (n=10000000)