{
    package Foo;
    sub new { bless {}, shift };
    sub sane { 42 };
    sub insane { 666 };
};

##</code><code>##

{
    package SaneFoo;
    use Class::Delegation send => 'sane', to => 'Foo';
    
    sub new {
        bless { Foo => Foo->new }, shift;
    };
};

##</code><code>##

use Test::More tests => 3;
use Test::Exception 0.15;

isa_ok my $o = SaneFoo->new, 'SaneFoo';
lives_and {is $o->sane, 42} 'sane worked';
dies_ok {$o->insane} 'insane failed';

__END__
# test results are:
1..3
ok 1 - The object isa SaneFoo
ok 2 - sane worked
ok 3 - insane failed

##</code><code>##

{
    package SaneFoo;
    use Carp;
    
    my %Foo = ();
    
    sub new {
        my $self = bless {}, shift;
        $Foo{$self} = Foo->new;
        return($self);
    };
    
    sub allows {
        my ($self, $method) = @_;
        return( $method eq "sane" );
    };
    
    sub AUTOLOAD {
        my $self = shift;
        our $AUTOLOAD;
        my ($method) = ($AUTOLOAD =~ m/([^:]+)$/);
        croak "$self cannot $method" unless $self->allows($method);
        $Foo{$self}->$method;
    };
                        
    sub DESTROY {
        my $self = shift;
        delete $Foo{$self};
    };
};