use strict;
use warnings;

package MyLocal;
use PadWalker qw(peek_my);

my %old_value;

sub new {
    my $self = shift;
    my %arg  = @_;

    my $h = peek_my($arg{level});
    $arg{h} = $h;
    bless \%arg;
}

sub set {
    my ($self, $variable , $value) = @_;

    if(! exists $old_value{$variable}) {
        $old_value{$variable} = ${ $self->{h}{$variable} };
    }
    ${ $self->{h}{$variable} } = $value;
}

DESTROY {
    my $self = shift;

    foreach my $var (keys %old_value) {
        ${ $self->{h}{$var} } = delete $old_value{$var};
    }
}

package main;

my $x = 1;
my $f = sub { $x };

{
    my $loc = MyLocal->new(level => 1);
    $loc->set('$x' => 2);
    print $f->(), "\n"; # => 2
}
print $f->(), "\n"; # => 1
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