use strict;
use warnings;

sub dequote {
   local $_ = @_ ? $_[0] : $_;
   s/^"//;
   s/"$//;
   s/\\(.)/$1/g;
   return $_;
}

{
   package MyTie;
   sub TIESCALAR { bless(\my $var, shift) }
   sub FETCH     { my $self = shift;
                   print("FETCH\n"); return $$self; }
   sub STORE     { my $self = shift; $$self = shift;
                   print("STORE $$self\n"); return $$self;}
}

tie my $var, 'MyTie';
$var = '"John \"Foo\" Bar"';

print dequote, "\n"
   foreach $var;