Beefy Boxes and Bandwidth Generously Provided by pair Networks
No such thing as a small change
 
PerlMonks  

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??

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; }

In reply to Answer: How can I create an array of filehandles? by QandAEditors
in thread files by vroom

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.
  • Log In?
    Username:
    Password:

    What's my password?
    Create A New User
    Chatterbox?
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others having an uproarious good time at the Monastery: (3)
    As of 2020-11-26 04:50 GMT
    Sections?
    Information?
    Find Nodes?
    Leftovers?
      Voting Booth?

      No recent polls found

      Notices?