537.pl

#!/usr/bin/env perl

use strict;
use warnings;
use 5.010;

use Data::Dumper;
$Data::Dumper::Sortkeys = 1;
$Data::Dumper::Terse = 1;
$Data::Dumper::Indent = 1;
$Data::Dumper::Quotekeys = 1;
sub cgi_dump { say &Dumper; };

use Attribute::Handlers;

my %USER;
sub UNIVERSAL::needs_auth : ATTR(CODE) {
    my ($pkg, $sym, $code, ) = @_;
    no warnings 'redefine';

    *{$sym} = sub {
        my $fun =  *{$sym}{NAME};
        if (!%USER) {
            say "$fun: not logged in";
            return;
        }

        goto &$code;
    }
}

sub t1 : needs_auth {
    say 't1';
}

sub t2 : needs_auth {
    say 't2';
}

say 'pre auth:';
t1;
t2;

%USER = (name => 'mysz', );

say 'post auth:';
t1;
t2;