die "Unknown is ${is}";
}
$spec->{builder} = '_build_'.$name if ($spec->{builder}||0) eq 1;
+ die "Invalid builder for $into->$name - not a string"
+ if exists $spec->{builder} and ref $spec->{builder};
if (($spec->{predicate}||0) eq 1) {
$spec->{predicate} = $name =~ /^_/ ? "_has${name}" : "has_${name}";
}