#!/usr/bin/perl -w
use strict;

my $lc_msg = 'message';
inplace_uc ($lc_msg);
print "$lc_msg\n";

sub inplace_uc 
{
   our $text; 
   local *text = \$_[0];  # equivalent to:
                          #  local *text = \shift;
   $text =~ tr/a-z/A-Z/;  # added $text =~
}

my $lc_msg_y = 'another_message';
inplace_uc2 (\$lc_msg_y);
print "$lc_msg_y\n";

sub inplace_uc2
{
     my $str_ref = shift;
     $$str_ref =~ tr/a-z/A-Z/;
}
# prints:
#MESSAGE
#ANOTHER_MESSAGE