# here $count and $private_func are undef
# add_to_count() sub_from_count() get_count() set_count() and widget()
# are the only ways to access $count and ($)private_func()

{
    # use a closure to keep peoples sticky fingers off $count
    my $count;

    # define a func totally private to this closure
    my $private_func = sub { [blah blah blah] }

    # now here are a couple of modifiers
    sub add_to_count { 
        ++$count 
    }
    sub sub_from_count { 
        --$count 
    }

    # and the usual couple of accessors....
    sub get_count { 
        $count 
    }
    sub set_count {
        my ($new_count, $user ) = @_;
        if ( $user = 'root' ) {    # OK, OK so it is a silly example!
            $count = $new_count;
          return $count;
        }
        else {
            warn "Only root can set count directly, use add/sub/get blah..."
          return undef;
        }
    }

    # and something silly to use our private func...
    sub widget {
        &$private_func(@_) if $moon_in_venus && $believe_that_sort of stuff;
    }
}

# here $count and $private_func are undef