my $obj = {};  # empty anonymous hash reference
bless $obj, "Some::Class";

##</code><code>##

package Some::Class;

my $obj = {};
bless $obj;    # blesses into "Some::Class"

##</code><code>##

$obj->method( 'foo' );        # @_ contains ( $obj, 'foo' )
Some::Class->method( 'foo' ); # @_ contains ( 'Some::Class', 'foo' )

##</code><code>##

package Some::Class;

sub new {
  my $first_arg = shift; # get the first argument
  my $class = ref($first_arg) || $first_arg;  

  my $self = {};         # create a new, anonymous reference;
  bless $self, $class:   # bless it into the class
  return $self;
}