package MyClass; use Moo; use Moo::Role(); sub BUILD { my ( $self, $args ) = @_; my $module = $args->{'num'} % 2 ? 'Odd' : 'Even'; warn "$args->{'num'} $self loading $module"; Moo::Role->apply_roles_to_object( $self, $module); return $self; }; sub baz { return 'qux'; } 1; #### sub baz { die "Died in ", __PACKAGE__; } #### 1 MyClass=HASH(0x19c12c0) loading Odd at MyClass.pm line 14. Loaded Odd at Odd.pm line 4. 1 MyClass__WITH__Odd=HASH(0x19c12c0)->bar at test.pl line 11. Died in Odd at Odd.pm line 11.