http://www.perlmonks.org?node_id=1026154


in reply to Re^3: Hash order randomization is coming, are you ready?
in thread Hash order randomization is coming, are you ready?

So, if I understand correctly, the code you posted is visibly broken and has been for a very long time.

Well yes, it is broken, that was my point for bringing it up :-). Whether it is visibly broken or not depends on whether you have any collisions. In the case you posted there are two sets of collisions, 4 and 1, and 3 and 0. (You can tell because they reverse each copy in earlier perls.) However if changed it to be 1,2,3,5,7,8 you would not have any collisions and the order would appear the same. Eg try:

my %hash = map { $_ => 1 } (1,2,3,5,7,8);

In 5.18 the order will be different for every hash. No exceptions. Here is what perlfunc will say in 5.18:

Hash entries are returned in an apparently random order. The actual r +andom order is specific to a given hash; the exact same series of operations on two hashes may result in a different order for each hash. Any inser +tion into the hash may change the order, as will any deletion, with the exc +eption that the most recent key returned by C<each> or C<keys> may be deleted without changing the order. So long as a given hash is unmodified you +may rely on C<keys>, C<values> and C<each> to repeatedly return the same o +rder as each other. See L<perlsec/"Algorithmic Complexity Attacks"> for details on why hash order is randomized. Aside from the guarantees provided here the exact details of Perl's hash algorithm and the hash traversal order are subject to change in any release of Perl.
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$world=~s/war/peace/g