I just thinking about something like this just two days ago! I've had to set up a heirarchy of modules to do something very similar, but the alternate dispatch system I employed was specific to those modules and not something that you could just drop in to any other heirarchy, like this is.
The problem can be stated like this: say you want a object to try to get_money(). Say the object is a member of the classes Executive::Enron, Citizen::American and Human::AbleBodied. So you try
$KenLay->get_money();. It so happens that Executive::Enron::get_money() will return a failure. However, method dispatch stops at this failure, without trying the methods in other classes. For the sake of argument, we'll call this a bad thing. (I'm speaking highly rhetorically here, ok? For a non-dark side example, consider object $YAPC, member of classes Herd::Camels and NonProfit::OfficiallyLicensed. Herd::Camels::get_money() contains 'goto &pass_hat;' but NonProfit::OfficialyLicensed::get_money() writes grant proposals.)
You can create wrapper methods or a dispatch table to explicitly call each fully-qualifed method in order, but that would be unusably brittle. You could use NEXT, but if the modules you're dealing with already exist, you'd have to rewrite all the modules (or at least the methods, in new subclasses) from the heirarchy that you are working with.
Thanks to the things I learned from Damian's Advanced Objects course (another satisfied customer!), I was able to devise a solution. But it wasn't particularly easy, and can't be simply carried over to other modules. I was just wondering if this sort of thing could be done in a portable fashion when I saw this. Thanks, domm!
"It's beat time, it's hop time, it's monk time!"
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