package foo;
use warnings;
use strict;

sub new {
    my $invocant = shift;
    my $class = ref($invocant) || $invocant;
    my $self = {@_};
    bless($self, $class);

    $self->{file} = 'bar';

    open my $handle, ">", $self->{file} || die "Cannot write to $self->{file}: $!\n";
    print $handle "FooBar";
    close $handle;

    return $self;
}

sub DESTROY {
    my $self = shift;

    print "In DESTROY()\n";
    unlink $self->{file};
}

1;

use warnings;
use strict;
$|++;

my $f = foo->new();
print "Sleeping for 5 sec ... ";
sleep(5);
print "Done\n";