tied.pl

package Foo;
use 5.010;
use strict;
use warnings;

sub TIESCALAR {
    my $class = shift;
    bless \(my $init = "initial value"), $class;
}

sub FETCH {
    my $self = shift;
    return $$self;
}

sub STORE {
    my $self = shift;
    $$self = shift;
}

sub foo {
    say "foo";
}

package main;
use 5.010;
use strict;
use warnings;

my $f = tie my $foo, 'Foo';

say $foo;

$f->foo;
(tied $foo)->foo;