Simply loading this module makes your constructors "strict". If your constructor is called with an attribute init argument that your class does not declare, then it dies. This is a great way to catch small typos. Your application can use Carp::Always to generate stack traces on 'die'. Previously all exceptions contained traces, but this could potentially leak sensitive information, e.g. My::Sensitive::Class->new( password => , extra_value => 'foo' );