interestingly enough, I used something (partly, at least) similar in a recent post of mine.

in my endless quest for Evil Things To Do, I was looking for a way to express this:

sub deref { my $ref = shift; return $$ref; }
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in a more succint way. the first thing, of course, was to get rid of $ref, and so I wrote:

sub deref { ${$_[0]} }
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but this is nothing sexy. so I thought, maybe I can get rid of $ref while still retaining the shift:

sub deref { ${shift} }
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but this doesn't work, and it took me a bit (and the help of B::Deparse) to understand why.

${shift} is interpreted by the parser as a way to write $shift, and of course it returns nothing.

so I realized that the Perl parser needs to be hinted to get shift as a keyword, and this can be done in (at least :-) 3 ways:

sub deref { ${shift@_} } # too much explicit
sub deref { ${+shift} }  # supersticious? cfr. Roger
sub deref { ${shift;} }
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the last one I find particularly surprising :-)