Larry Wall writes:
> Anyway, this all implies that use of a role as a method name defaults to
> returning whether the type in question matches the subtype. That is,
> when you say
>
> $foo.true
>
> it's asking whether the Boolean property fulfills the true constraint.
> When you say
>
> $bar.red
So are you saying that, eg.
class Something does Color {...}
my Something $flib;
if $flib.red { print "Flib is red" }
if $flib.true { print "Should be an error before now" }
Since Something doesn't Boolean, true would be a "method not found"
error?
If that's the case, how do we attach out-of-band properties on objects
that don't expect them, but only some of them (as was the original
intent for properties, IIRC):
my role onlyonced;
sub onlyonce($arg is rw) {
die "onlyonce called twice on the same value" if $arg.onlyonced;
$arg but= onlyonced;
}
Either that doesn't work at all, because you get an "onlyonced not
found" error, or it works because onlyonced is a declared role. But
in the latter case I worry about namespace pollution.
It's clear that I don't entirely understand all of this yet (er, as much
as there is to understand... yet).
Luke
