use strict;
use warnings;
use Data::Dump::Streamer;

my %foo = (a => 'b', c => 'd');
my @stack;

my %newFoo = (x => 'b', y => 'd');

push @stack, {%foo};
%foo = %newFoo;
print "Using \%newFoo\n";
Dump (\%foo);

# do stuff with temporary foo

%foo = %{pop @stack};
print "restored original \%foo\n";
Dump (\%foo);