package GenObj;

my %methods = (
  name => sub { $_[0]{DATA}{name} },
  setname => sub { $_[0]{DATA}{name} = $_[1] },
  # ...
);

sub new {
  my ($class) = @_;
  bless { DATA => {}, METHODS => {%methods} }, $class;
}

AUTOLOAD {
  (my $method = $AUTOLOAD) =~ s/.*:://;
  $_[0]{METHODS}{$method} ?
    goto &{$_[0]{METHODS}{$method}} :
    die "unsupported method $method for object";
}

package main;

$foo = GenObj->new;
$foo->setname("Jeff");
print $foo->name;

##</code><code>##

$x = new GenObj;       # ref($x) eq 'GenObj::a'
$y = new GenObj -foo;  # ref($y) eq 'GenObj::b'
$x->get_foo;           # calls $x->GenObj::get_foo
$y->get_foo;           # calls $y->GenObj::b::get_foo

##</code><code>##

package GenObj;

# the following methods can be generated
# automatically with one of the Class::
# modules...

# these are the EXPECTED inherited methods
# of GenObj objects
sub set_name { $_[0]{name} = $_[1] }
sub get_name { $_[0]{name} }
sub set_age { $_[0]{age} = $_[1] }
sub get_age { $_[0]{age} }


my $CHILD = 'a';

sub new {
  no strict 'refs';  # naughty things transpire

  my $class = shift;
  my $obj = bless {}, "${class}::$CHILD";

  @{"${class}::${CHILD}::ISA"} = ($class);
  for (map s/^-//, @_) {
    *{"${class}::${CHILD}::get_$_"} =
      \&{"${class}::Sub::get_$_"};
    *{"${class}::${CHILD}::set_$_"} =
      \&{"${class}::Sub::set_$_"};
  }

  return $obj;
);


package GenObj::Sub;

# these are the specialized methods
# to be inherited on demand
sub set_name { $_[0]{name} = condense($_[1]) }
sub get_name { expand($_[0]{name}) }
sub set_age { $_[0]{age} = age2sec($_[1]) }
sub get_age { sec2age($_[0]{age}) }

# these are some utility functions
# as called above
sub condense;
sub expand;
sub age2sec;
sub sec2age;

1;

##</code><code>##

use GenObj;
my $normal   = new GenObj;
my $diffage  = new GenObj -age;
my $diffname = new GenObj -name;
my $diffboth = new GenObj -age, -name;

$normal->set_age(10);  # GenObj::set_age
$normal->get_name;     # GenObj::get_name

$diffage->set_age(10);  # GenObj::Sub::set_age
$diffage->get_name;     # GenObj::get_name

$diffname->set_age(10);  # GenObj::set_age
$diffname->get_name;     # GenObj::Sub::get_name

$diffboth->set_age(10);  # GenObj::Sub::set_age
$diffboth->get_name;     # GenObj::Sub::get_name