perl -e 'use Scalar::Util; $ref = qr//; print "$ref\n"; print Scalar::Util::refaddr($ref)."\n";'
(?-xism:)
0

##</code><code>##

perl -e 'use Scalar::Util; $ref = qr//; print "$ref\n"; print Scalar::Util::refaddr($ref)."\n";'
(?-xism:)
135576940

##</code><code>##

Class-Std-Utils-v0.0.3# prove t/ident.t 
t/ident......ok    
All tests successful.