#test.pl
use lib '.';
use Foo;
use Benchmark ':all';
 
my $f = bless {}, 'Foo';
 
timethese(0, {
    set_inherited_class  => sub {Foo->set_inherited('bar', 'baz')},
    set_inherited_object => sub {$f->set_inherited('bar', 'baz')}
});

##Foo.pm
package Foo;
use Scalar::Util qw/blessed reftype/;

sub set_inherited {
    my ($self, $set, $val) = @_;

    if (blessed $self) {
        if (reftype $self eq 'HASH') {
            return $self->{$set} = $val;
        } else {
            croak('Cannot set inherited value on an object instance that is not hash-based');
        };
    } else {
        no strict 'refs';

        return ${$self.'::__cag_'.$set} = $val;
    };
}

1;