Anonymous Subroutines as Objects

Why would you want to do that?
Consider this problem with conventional objects:

        sub new {
          my ($package, $name, $balance) = @_;
          my $self = { NAME => $name, BALANCE => $balance };
          bless $self => $package;
        }
        ...

        my $object = BankAccount->new('Fred', 100.00);
        $object->{BALANCE} = 1000000000000.37;

Wasn't that data supposed to be encapsulated?
I guess it wasn't encapsulated very well
This is impossible with function objects