For a while, all the winning solutions on the Perl golf site (not available, last I checked :-() were substitutions-within-substitutions. So my conjecture is that this comes from a golf. Or someone who is very golf-oriented.
Caution: Contents may have been coded under pressure.

In reply to Re^2: Need explanation: what \$_ and ${} do by Roy Johnson
in thread Need explanation: what \$_ and ${} do by Anonymous Monk

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