gistfile1.pl

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

print "Orig   : " . \&Carp::confess . "\n";
my $copy = \&Carp::confess;
print "Copy   : $copy\n";
my $new = sub {};
print "New    : $new\n";

{
    no warnings 'redefine';
    *Carp::confess = $new;
    print "Changed: " . \&Carp::confess . "\n";
    *Carp::confess = $copy;
    print "Revert : " . \&Carp::confess . "\n";
}