substr($str, $max - 3) = '...';
  }
  return $str;
}

# Takes two packages and an optional cache.  Says whether the
# first inherits from the second.
#
# Recursive versions of this have to work to avoid certain
# possible endless loops, and when following long chains of
# inheritance are less efficient.
sub trusts {
    my $child = shift;
    my $parent = shift;
    my $cache = shift || {};
    my ($known, $partial) = get_status($cache, $child);
    # Figure out consequences until we have an answer
    while (@$partial and not exists $known->{$parent}) {
        my $anc = shift @$partial;
        next if exists $known->{$anc};
        $known->{$anc}++;
        my ($anc_knows, $anc_partial) = get_status($cache, $anc);
        my @found = keys %$anc_knows;
        @$known{@found} = ();
        push @$partial, @$anc_partial;
    }
    return exists $known->{$parent};
}

# Takes a package and gives a list of those trusted directly
sub trusts_directly {
    my $class = shift;
    no strict 'refs';
    no warnings 'once'; 
    return @{"$class\::CARP_NOT"}
      ? @{"$class\::CARP_NOT"}
      : @{"$class\::ISA"};
}

1;