package Person;
use Moo;
 
has name => (is => 'rw');
has age  => (
    is  => 'rw',
    isa => sub {
       die "'$_[0]' is not an integer!"
          if $_[0] !~ /^\d+$/;
    },
);
 
1;

##</code><code>##

use strict;
use warnings;
use 5.010;
 
use Person;
my $student = Person->new( name => 'Foo', age => 22 );
say $student->name;
say $student->age;
$student->age('young');
say $student->age;