So I have no where I can assign the newly generate sub.

Maybe with Data::Swap, you can work around this problem. I haven't tried yet, but I'm thinking of something like

use Data::Swap;

sub myhandler : ATTR(CODE) {
    my ($p, $s, $r, ...) = @_;
    swap $r, \my $o;
    swap $r, sub {
        # code
        &$o;
    };
}
[download]

I have no idea if this would work.

Juerd # { site => 'juerd.nl', plp_site => 'plp.juerd.nl', do_not_use => 'spamtrap' }