use strict;
use warnings;

use Sub::ScopeFinalizer qw( scope_finalizer );

{
   package Tied;
   use Tie::Scalar;
   our @ISA = qw( Tie::StdScalar ); 
   sub FETCH { return ${ $_[0] }++ }
}

sub localiser {
   my $var_ref = \$_[0];
   my $saved = $$var_ref;
   $$var_ref = $_[1];
   return scope_finalizer { $$var_ref = $saved };
}

{
   tie our $tied_pkg, 'Tied';
   $tied_pkg = 'a';
 
   print $tied_pkg;          # a
   {
      local $tied_pkg = 'x';
      print $tied_pkg;       # x
      print $tied_pkg;       # y
      print $tied_pkg;       # z
   }
   print $tied_pkg;          # b
   print $tied_pkg;          # c
   print "\n";
}

{
   tie my $tied_lex, 'Tied';
   $tied_lex = 'a';
 
   print $tied_lex;          # a
   {
      my $restorer = localiser($tied_lex, 'x');
      print $tied_lex;       # x
      print $tied_lex;       # y
      print $tied_lex;       # z
   }
   print $tied_lex;          # b
   print $tied_lex;          # c
   print "\n";
}
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