#!/usr/bin/perl

use strict;
use warnings;
my $usemod;     # if you initialize `my $usemod = 0;`, then the BEGIN block's assignment to $usemod is overridden, which you don't want
our $Registry;  # this will be overridden by Win32::TieRegistry's export of $Registry if in Windows, but

BEGIN {
    local $\ = "\n";
    if( $^O eq 'MSWin32' ) {
        eval {
            require Win32::TieRegistry;
            Win32::TieRegistry->import( Delimiter => '/' );
            $usemod = 1;
        }
    }
}

if ($usemod) {
    my $IEKey = $Registry->{'HKEY_CURRENT_USER/Software/Microsoft/Internet Explorer/Main/'};
    print "IEKey = '$IEKey'\n";
} else {
    print "None of that stuff here\n";
}