return void;

There are a few corrections that were needed from my .WALK talk yesterday. Having the Rakudo pumpking sitting next to you makes answering questions much easier.

First, moritz_ strongly suggested I post working code and not off-the-cuff code anymore. His argument was that it further perpetuates the meme that Perl 6 is vapor. So here’s a properly working example:

class A {
    method baz { ... };
    method bar { ... };
};

class B is A {
    method baz { ... };
    method icanhaz { ... };
};

class C is B {
};

class D is A {
    method ucanhaz { ... };
};

my @candidates;
my C $c .= new;
@candidates = $c.WALK(:name<baz>);
say @candidates.map(*.name).join(', ');
@candidates = $c.WALK(:name<icanhaz>);
say @candidates.map(*.name).join(', ');

So the obvious correction there is the change to class. This is because modules cannot inherit. Also, the named parameters were supposed to use <> or quotes. The say calls were added to see the results immediately (aestetics).

Also, it seemed that in my attempt to understand WALK, I misread the entire intent of the returned results. The WALK iterator will in fact return callable methods (Code objects?). Those methods can then be called with the $* and $+ operators (as discussed in S12). The correct output is:


baz, baz
icanhaz


The two baz methods are B::baz and A::baz, while the icanhaz is just B::icanhaz. Since multi method dispatch never truely hides methods, similar to C++ (Base::method) and Java (super.method), A::baz is still available for dispatching.

Lastly, :name is not required, since it will return all methods. :name, hence why it was bundled in the filter parameter list, merely filters out method name matches.

That should wrap the loose ends. I hope the attendees enjoyed learning about method dispatch and WALK. I’m soliciting for next month’s talk if anyone wants to volunteer.