#!/usr/bin/perl
use v5.14;
use Data::Dumper;

BEGIN {
    package Err;

    require Exporter;
    our @ISA = qw(Exporter);
    our @EXPORT = qw(err);

    use overload q("") => sub { my $e = shift; "ERROR $e->[0]: $e->[1] \n".Carp::longmess()};

    sub new { my $class = shift; bless $_[0], $class }

    sub err { __PACKAGE__->new([@_]) }
}

package main;
BEGIN { Err->import }
use Carp;

sub f {
    g();
}

sub g {
    die err(403, "Permission denied");
}

f();

##</code><code>##

ERROR 403: Permission denied 
 at ./test.pl line 28.
	main::g() called at ./test.pl line 24
	main::f() called at ./test.pl line 31