Re: How can I create an array of filehandles?

[CharlesClarkson]

As of Perl 5.6.0 file handles can be autovivified. So it is possible to open a file like this:

open my $fh, '>', $file_name or die "Cannot open $file_name: $!";

This allows us to refer to the filehandle as $fh. The following sub returns a hash keyed to the file names:

my %handles = get_write_handles(qw/col1.txt col2.txt col3.txt/);

sub get_write_handles {
  my @file_names = @_;
  my %file_handles;
  foreach (@file_names) {
    open my $fh, '>', $_ or next;
    $file_handles{$_} = $fh;
  }
  return %file_handles;
}

Note that files that cannot be opened are not defined in the hash. Now the files can be referred to from %handles:

print { $handles{'in.txt'} } "something\n";

or:

foreach (values %handles) {
  print $_ "something\n";
}

To return an array we need to decide what happens if a file can't be opened. This sub dies:

sub get_read_handles {
  my @file_names = @_;
  my @file_handles;
  foreach (@file_names) {
    open my $fh, '<', $_ or die "Yikes $_: $!";
    push @file_handles, $fh;
  }
  return @file_handles;
}

While this will return undef for failed opens:

sub get_append_handles {
  my @file_names = @_;
  my @file_handles;
  foreach (@file_names) {
    if (open my $fh, '>>', $_) {
        push @file_handles, $fh;
    } else {
        push @file_handles, undef;
    }
  }
  return @file_handles;
}