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

##</code><code>##

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;

##</code><code>##

STORE "John \"Foo\" Bar"
FETCH
STORE
FETCH
Use of uninitialized value in concatenation (.) or string at 561931.pl line 18.
STORE
FETCH
Use of uninitialized value in substitution (s///) at 561931.pl line 6.
FETCH
Use of uninitialized value in substitution (s///) at 561931.pl line 7.
FETCH
Use of uninitialized value in substitution (s///) at 561931.pl line 8.
FETCH
STORE
Use of uninitialized value in print at 561931.pl line 25.

##</code><code>##

use strict;
use warnings;

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

$_ = 'abcd';
/\G .. /gcx;
print(pos(), "\n");

dequote('"John \"Foo\" Bar"');

print(pos(), "\n");

##</code><code>##

2
Use of uninitialized value in print at 561931.pl line 18.

##</code><code>##

2
2

##</code><code>##

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

##</code><code>##

STORE "John \"Foo\" Bar"
FETCH
John "Foo" Bar

##</code><code>##

2
2