sub new {
    my ($class) = @_;
    return bless({
        ACCOUNT => undef,
        NAME    => undef,
        BALANCE => 0,
    }, $class);
}

sub _access {{
    my $self  = shift;
    my $field = shift;
    if (@_) { $self->{$field} = shift; }
    return $self->{$field};
}

sub account { splice(@_, 1, 0, 'ACCOUNT'); goto \&_access; }
sub name    { splice(@_, 1, 0, 'NAME'   ); goto \&_access; }
sub balance { splice(@_, 1, 0, 'BALANCE'); goto \&_access; }

...