sub foo {
  alias $_[0] => my $byRef;
  ...
  $byRef += $result;
}

##</code><code>##

use strict;
use warnings;
use Lexical::Alias;

my $orig = 1;
my $alias = 99;
alias $orig => $alias;
print "$orig = $alias\n";

sub foo {
	my $orig = 1;
	my $alias = 99;
	alias $orig => $alias;
	print "foo(): $orig = $alias\n";
}

foo();

##</code><code>##

 1 = 1
 foo(): 1 = 99

##</code><code>##

 1 = 1
 foo(): 1 = 1

##</code><code>##

This is perl, v5.8.0 built for MSWin32-x86-multi-thread
(with 1 registered patch, see perl -V for more detail)

Copyright 1987-2002, Larry Wall

Binary build 805 provided by ActiveState Corp. http://www.ActiveState.com
Built 18:08:02 Feb  4 2003

##</code><code>##

sub foo {
  alias $byRef => $_[0];
  ...