package Simple;

use Class::MethodMaker
    get_set         =>  [ qw/ a b / ],
    new_with_init   =>  'new';

sub init {
    my ($class, %args) = @_;

    my %default = (
        'b' =>  'default'
    );

    %args = (%args, %default);
    bless \%args, $class;
}

##</code><code>##

use Carp;

%args = (%args, %default);
foreach (keys %args) {
    carp( 'Unknown argument to init subroutine - ', $_ ) unless exists $default{$_};
}
bless \%args, $class;