Roles driven by events

Having a problem with the following role in Perl 5:

  package PIPs::ResultSource::Role::HasTags;
  use Moose::Role;

  requires 'do_setup';
  after 'do_setup' => sub { ... };

So far this has worked really well, aside from that one class which didn't call 'do_setup'.  Oops.

Requiring methods and requiring methods to be called are different things.  It might be a nice feature to have roles which tie into "events".  If a particular condition doesn't hold true by, say, INIT time, the role fails.

How would I implement something like that in Perl 6?  Or am I just looking at this wrong?

Cheers,
Ovid
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• Roles driven by events by Ovid
• Re: Roles driven by events by Jonathan Worthington
• Re: Roles driven by events by Jon Lang