MooseX::Attribute::ChainedClone3pm

  package Test;
  use Moose;
  has debug => (
      traits => [ 'ChainedClone' ],
      is => 'rw',
      isa => 'Bool',
      default => 0,
  );
  sub complex_method
  {
      my $self = shift;
    
      #...
    
      print "helper message" if $self->debug;
    
      #...
  }
  
  sub clone {
      my $self = shift;
      # custom clone code here
      # defaults to:
      return bless { %$self }, ref $self;
  }
  1;

Which allows for:

    my $test = Test->new;
    $test->debug(1)->complex_method; # debug enabled
                                     # complex_method is called on a cloned instance
                                     # with debug set to 1
    $test->complex_method;           # debug is still disabled on $test
    $test->debug(1); # returns a cloned $test instance with debug set to 1
    $test->debug;    # returns 0