From the OP: 
${@$a}[0]

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I had to stare at that for a bit and then do a little experiment: 
>perl -wMstrict -le
"my @ra = qw(a b c d);
 my $ar = \@ra;
 print ${  ra}[2];
 print ${ @ra}[2];
 print ${ $ar}[2];
 print ${@$ar}[2];
"
c
c
c
c

[download]
Sure enough, it works! I'm gobsmacked!

Needless to say, I've never seen the second and fourth forms of the array access expression, the ones using the  @ sigil apparently redundantly. These forms are certainly not widely used, but are they ever used? I.e., is there any situation in which the  @ sigil must be used in this way?

Update: Added $ that was MIA in ${@$a}[0].

In reply to Re^3: "strict" violation on "sort" command with perl 5.10 by AnomalousMonk
in thread "strict" violation on "sort" command with perl 5.10 by mstet

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