perl unicode: combined vs full unicode graphemes

http://www.effectiveperlprogramming.com/blog/102

-----
use charnames ':full';

my $string =
"\N{LATIN SMALL LETTER A WITH DIAERESIS}"
. "\N{LATIN SMALL LETTER A}"
. "\N{COMBINING DIAERESIS}"
;
ää
------
my (@g) = $string =~ /(.)/g;

say scalar(@g); # 3
ä a¨
-----
my (@g) = $string =~ /(\X)/g;

say scalar(@g); # 2

ä ä

------

my $precomposed =
"\N{LATIN SMALL LETTER A WITH DIAERESIS}";

my $combined =
"\N{LATIN SMALL LETTER A}" .
"\N{COMBINING DIAERESIS}";
------

if ($precomposed eq $combined) {
say 'equal';
} else {
say 'unequal';
}
unequal
------
use Unicode::Normalize;

my $postcomposed = NFC($precomposed);

if ($precomposed eq $postcomposed) {
say 'equal';
} else {
say 'unequal';
}
equal


------
use open IO => ':utf8';

use open OUT => ':shiftjis';

use open IN => ':cp1251';

open my ($ofh), '>:utf8', $filename;

open my ($ifh), '<:encoding(iso-8859-1)', $filename;

------

But what about command line arguments?
use I18N::Langinfo qw(langinfo CODESET);
use Encode qw(decode);

my $codeset = langinfo(CODESET);

@ARGV = map { decode $codeset, $_ } @ARGV;
------


------