use Params::Validate 'validate_pos';
use constant FOOBAR_TYPE => { can => [ qw[ print flush frobnicate ] ] };

sub bar {
    my $foobar = validate_pos( @_, FOOBAR_TYPE );
}

##</code><code>##

use Params::Validate 'validate_pos';
use constant FOOBAR_TYPE => { callbacks => { interface => sub { Interface::has( FooBar => $_[0] ) } } };

sub bar {
    my $foobar = validate_pos( @_, FOOBAR_TYPE );
}

package FooBar;
use Interface 'FOOBAR';

...