my %Files;

sub open_file {
    my $file_name = shift;
    die "$file_name is already open" if exists $Files{$file_name};
    open my $FH, '>', $file_name or die "$file_name open error: $!";
    $Files{$file_name} = { COUNT=>0, FH=>$FH };
}

sub file_handle {
    my $file_name = shift;
    die "$file_name: Hasn't been opened yet" if ! exists $Files{$file_name};
    return $Files{$file_name}{FH};
}

sub file_counter {
    my $file_name = shift;
    die "$file_name: Hasn't been opened yet" if ! exists $Files{$file_name};
    return $Files{$file_name}{COUNT};
}
    
sub write_to_file {
    my $file_name = shift;
    my @stuff_to_print = @_;
    die "$file_name: Hasn't been opened yet" if ! exists $Files{$file_name};
    my $file = $Files{$file_name};
    my $FH = $file->{FH};
    print $FH @stuff_to_print;
    ++$file->{COUNT};
}

for my $file ('foo', 'bar', 'baz') {
    open_file($file);
}

for my $file ('foo', 'foo', 'baz', 'foo', 'bar') {
    my $count = file_counter($file);
    write_to_file($file, "Count is $count\n");
}