in reply to Callback multiplexer
Of course, this can be done. Set up lots of callbacks that share a hash; delete keys from that hash whenever a task finishes; call the megacallback when the hash is empty. I wonder if there's a more civilized way of doing it, maybe some CPAN module?
I find this approach pretty civilized. I am sure any module providing that functionality will actually do it in this same way under the hood.
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