On IRC, ruoso wrote:

wayland, one important thing I didn't mention in the mail is that I understand that if some attribute is going to be undefined for some cases in a Role, then it doesn't belong in that role, but in a more specialized one...
the good thing about roles is that they don't require an hierarchy

(which is what makes the Java API so terrible)

One problem (as I mentioned elsewhere just now) is that I'm trying to specify an API with optional parts. Maybe I should stop using roles for this :).

I'd argue, also that Undefined isn't really undefined, it's really a value. For example, say you malloc some memory in C, there could be anything in it; it really *is* undefined. Whereas the Perl 6 "Undefined" value is guaranteed to always return "Undefined".

I guess it's because I was expecting people using a composition of Tree to go:

        if(! defined($footree.root)) { warn "Unrooted tree"; }

        ...instead of

        if(! $footree.has('$root')) { warn "Unrooted tree"; }
        # Does this even work???

        Or maybe even:

        try {
                CATCH {
                        when /Error: has no attribute named 'root'/ {
                                warn "Unrooted tree";

        ...you can see why I prefer the first one :).

        Anyway, HTH,

| Name: Tim Nelson                 | Because the Creator is,        |
| E-mail: wayl...@wayland.id.au    | I am                           |

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