perl -e 'my $foo = \*STDOUT; print $foo "Foo!$/"'

##</code><code>##

my %platfile = (
    NT => 'nt.html',
    UNIX => 'unix.html',
    MAIL => 'mail.html'
);
#...
{
    open my $out, '>>', "$filepath/$platfile{$classHash{$class}}"
      or die $!;
    # ...
}