Yeah this is a nasty cryptic and totally groovy way to do things. I think I understand how it works, let see if I am right...

my $node=\\my %hash;
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This sets $node to be a reference to a reference to %hash.

$node = \$$node->{$_} for @keys;
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So this says to make node become equal to a reference to the slot $_ in the current hashref that $node references (foreach element in the list). It might be clearer to write it like so:

$node = \(${$node}->{$_})
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Basically the idea of this is to take advantage of perls autovivification. The double reference is a nice way to ensure that we are always pointed at the slot that holds the previous key. If that value is undef, then it will be autovivified when it is used as a reference.

$$node = "value";
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Stick the final value in.

Cool eh? juerd++ and japhy++

--- demerphq
my friends call me, usually because I'm late....