use Types::Standard qw( is_ArrayRef is_HashRef ); use Carp qw( croak ); sub process_data { my ($self, $data) = @_; if (is_ArrayRef($data)) { $self->_process_value($_) for @$data; } elsif (is_HashRef($data)) { $self->_process_value($_) for values %$data; } else { croak "Could not grok data"; } }