Just a nit - while your approach is far better than mine and less convoluted, there's no OR and no cache, so there's no Orcish (or-cache) Maneuver. That would be (from Shlomo Yona's Perl lectures 2002):

The Orcish Maneuver -- example

keys my %or_cache = @in;
@out = sort {
    ($or_cache{$a} ||= KEY($a))
    cmp
    ($or_cache{$b} ||= KEY($b))
} @in;

[download]

The first part of the sortsub sees if the sortkey for $a is cached.

If not, it extracts the value of the sortkey from the operand and caches it.

The sortkey for $a is then compared to the sortkey for $b.

Anyways, salva++ for simplifying things :-)

--shmem 

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}

In reply to Re^3: Sorting Index of An Array by shmem
in thread Sorting Index of An Array by neversaint

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