Here's another take on the first example that only returns one line at a time until all filehandles are exhausted and returns undef when that happens. 

sub gen_fh_iterator {
  my ( $current, @fhs ) = @_;
  return sub {
    my $line;
    while ( ! defined $line && @fhs ) {
      $line = <$current>;
      $current = shift @fhs
        if not defined $line;
    }
    return $line;
  };
}

my $file_iter = gen_fh_iterator( @fhs );
while ( my $line = $file_iter->() ) {
  print "$line\n";
}

[download]

In reply to Re: How To: Make An Iterator by kelan
in thread How To: Make An Iterator by Limbic~Region

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, details, 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, summary, 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.