#/usr/bin/perl
use strict;
use warnings;

use IO::File;

use 5.010;

my $filename = shift @ARGV;

my $fh = IO::File->new($filename, 'r');

my $fh_iterator = sub {
    my $fh = shift;

    my $line = $fh->getline;
}

while (my $line = $fh_iterator->($fh)) {
    # do stuff to $line
}

##</code><code>##

    $line .= $fh_iterator->($fh) if $line =~ /\\\n/

##</code><code>##

sub fh_iterator {
    my $fh = shift;

    my $line = $fh->getline;
    $line .= fh_iterator($fh) if $line =~ /\\\n/;
    return $line;
}