__autoflush.pl

# To avoid IO::Handle and other IO::* "autoloading" when using $fh->autoflush(1)
sub __autoflush($) {
    my $fl_have2select = defined(my $fh = $_[0]);
    # previously selected file handler
    my $prv_sel_fh;
    if ( $fl_have2select and ! eval {
        no warnings;
        $prv_sel_fh = select $fh;
        print '' or die "$!\n";
    }) {
#        __out_to_tty '>>', __chomp(\$@), '<<';
        defined($prv_sel_fh) and select($prv_sel_fh);
        return
    }   

    my $prv_af = $|;
    my $new_af = ($#_ > 0) && ! $_[1] ? 0 : 1;
    ( !! $prv_af ^ !! $new_af ) and $| = $new_af;

    $fl_have2select and fileno($prv_sel_fh) != fileno($fh) and select($prv_sel_fh);

    return $prv_af
}