use strict;
use warnings;
use XML::Simple;

my $xs = XML::Simple->new(ForceArray=>['httpd']);
my $s = do { local $/=undef; <DATA> };
my $conf = $xs->XMLin($s);
my $ct = 0;
foreach my $httpd ( @{$conf->{httpd}} ){
  $ct++;
  if( ref($httpd) eq 'HASH' ){
    $httpd->{number} = $ct;
  }else{
    $httpd = { content=>$httpd, number=>$ct };
  }
}
my $xml = $xs->XMLout($conf);
print $xml;


__DATA__
<x>
<httpd><![CDATA[
...1st piece of httpd configuration
]]></httpd>
<httpd><![CDATA[
...2nd piece of httpd configuration
]]></httpd>
</x>
[download]

The equivalent code in XML::Twig is below. Note that you could write very similar code with XML::LibXML (the difference being that you would use XPath to find the httpd elements and one (or more likely several!) DOM method(s) to add the attribute. If your initial file is big and you don't want to load it entirely in memory you can switch to using XML::Twig twig_handlers or twig_roots options, see the docs if necessary.

#!/usr/bin/perl -w

use strict;
use warnings;

use XML::Twig;

# keep_spaces is not completely necessary, it's just
# there to keep the initial formating of the file
my $twig= XML::Twig->new( keep_spaces => 1)
                   ->parse( \*DATA)
                  ;

my $i=0;

foreach my $httpd ( $twig->root->children( 'httpd'))
  { my $config= $httpd->text;
    # do something with $config
    $httpd->set_att( config => ++$i); 
  }

$twig->print;

__DATA__
<file>
<httpd><![CDATA[
...1st piece of httpd configuration
]]></httpd>
<not_httpd />
<httpd><![CDATA[
...2nd piece of httpd configuration
]]></httpd>
</file>
[download]

Thanks, but, accidentally, Dumper($_) positioned in foreach body shows me variable with CDATA content only, the attribute is lost.
I wish so simple thing, but I am not able to force XML::Simple to put both content and attribute of <httpd> element to some structure, which is an item of array @{$conf->{httpd}} :(
Perhaps I am too tired or too dumb now, but my XML::Trivial is much more simple to use... I publish it after some real experiences, luckilly to avoid headache of some programmers similar to me.

Since it appears you are stuck with XML::Simple, you may also wish to look at:

XML::Simple is doing too much for me! Help please.
XML::Simple "transforming data"
XML::Simple help

for more on XML::Simple and its Keeproot, ForceArray, RootName, and NoAttr options.

These might also be helpful:

Perl-XML Frequently Asked Questions
Frequently Asked Questions about XML::Simple

HTH,

Hi pajout,

Try XML::Twig

You do have method set_att using that you can set attributes to an element.

regards,
Murugesan kandasamy.

Thanks for advice, but I need to hack existing code only, I cannot do such great jump :)

my $xml = XML::Simple->new(ForceArray=>['httpd'],
                           ContentKey=>'-content');
...
my $parsed = ...;
foreach {@{$parsed->{httpd}}
  if (ref($_) eq 'HASH') {
    #element has attibute(s)
    #do something with $_->{attr_name} and/or $_->{content}
  } else {
    #element has text node only
    #do something with $_, which is scalar text
  }
}
[download]

I'm pleased you found a solution to your problem. You might be interested in this tutorial which compares using XML::Simple to XML::LibXML and demonstrates that the libxml code can be simpler and more powerful:

• Stepping up from XML::Simple to XML::LibXML

Many thanks for reply. I like libxml & libxslt, but now I have no real experience with it - we GingerAlliance guys use XML::Sablotron :))
Now I deside to include libxml(2) into my own project, instead of sablotron, so I will study XML::LibXML intensively.
My wish is to have very simple tool giving parsed short xml configuration files as perl structure, for read-only random access. So, firstly parse all syntacticall objects presented (elements, text nodes, notes, CDATAs, PIs,...) and check well-formedness, optionally check validity (RelaxNG rather than dtd) and inject it into perl without lose of informations. And perl subroutines must know, where are the relevant information pieces, traversing via very simple API, without any expectations about parameters of xml to perl structure transformation.
XML::Simple is great, but too great to use it with my requirement, imho...