my $x = \" VERY VERY BIG STRING .....";
  my $len = length( $$x );

##</code><code>##

     sub foo { my $s = shift; my $r = \$s; print "FOO ($r)\n" } 
     my $X = "SOMESTRING"; 
     my $O = \$X; 
     my $R = \$X; 
     print "NOTFOO ($R,$O)\n";                                           
     foo( $$R );

##</code><code>##

NOTFOO (SCALAR(0x9393f8),SCALAR(0x9393f8))
FOO (SCALAR(0x9394a0))

##</code><code>##

     sub foo { my $r = \$_[0]; print "FOO ($r)\n" } 
     my $X = "SOMESTRING"; 
     my $O = \$X; 
     my $R = \$X; 
     print "NOTFOO ($R,$O)\n";                                           
     foo( $$R );

##</code><code>##

NOTFOO (SCALAR(0x1ac23e8),SCALAR(0x1ac23e8))
FOO (SCALAR(0x1ac23e8))