sample.pl

sub _get_all_attrs {
    my @todo = @_; 
    my %seen;
    my @all;
    while (my $pkg = shift @todo) {
        next if $seen{$pkg}++;
        my $found = $META{$pkg};
        push @all => @$found if $found;

        no strict 'refs';
        my $isa = \@{"$pkg\::ISA"};
        push @todo => @$isa if @$isa;
    }   

    return \@all;
}