Re: How to remove the certain element of an object

[tobyink]

Your OO design seems questionable - you seem to be using the Person class to represent individual people (good!) but also to represent collections of people/populations. Use two separate classes

package Nation {
  use Moose;
  has population => (is => 'ro', isa => 'ArrayRef[Person]');
  ...;
}

package Person {
  use Moose;
  has name => (is => 'ro', isa => 'Str');
  ...;
}

I'm not 100% clear on exactly what you want to do. Do you want to remove people from the population when $person->need_to_go is true? If so, I'd probably do something like this:

use List::MoreUtils qw(part);

# Split population into people to keep, and people to go...
my ($keep, $go) = part { !!$_->need_to_go } @{ $people->population };

# Set the population to just the people we want to keep.
@{ $people->population } = @$keep;