Piers,
On Oct 12, 2005, at 5:22 AM, Piers Cawley wrote:
We definitely have two instances of A since, B.isa(::A). We also have
a fragile implementation of count.
:)
Sorry, I purposefully made it a kludge as that is usually the way the
example is shown in most tutorials about class methods.
class A {
our %.count_of
method count (Class $c:) { %.count_of{$c} }
method BUILD {
$class = ($?SELF.class)
@countable_ancestors = $class.ancestors.uniq.grep :{.isa(::A)}
You can use the MRO here, which is an already linearized list of the
inheritance tree (in C3 order) with all duplicates removed.
for $class, [EMAIL PROTECTED] -> $c { %.count_of{$c}++ }
}
Where we're assuming I've got the syntax of 'for' right, and that
'ancestors' is a class method that returns all of a class's
ancestors. This might not work too well in the face of a dynamic
inheritance tree, but it should be possible to work around. Something
like this might work:
Class A {
our %.instance_count_of
method count (Class $c: ?$with_descendents = undef) {
my @interesting_classes = $c;
if $with_descendents {
push @interesting_classes, *($c.all_subclasses);
}
[+] %.instance_count_of(@interesting_classes)
}
method BUILD {
%.instance_count_of($?SELF.class)
}
}
Where we're assuming that a class can find all its subclasses
--
Piers Cawley <[EMAIL PROTECTED]>
http://www.bofh.org.uk/
