<root>
 <foo x="5">
   <bar>hello</bar>
   <baz>world</baz>
 </foo>
</root>

=>

root(
 foo( x => 5,
  bar("hello"),
  baz("world")
 )
)
[download]

$xml = <<'*END*';
<doc>
 <person>
  <fname>Jane</fname>
  <lname>Luser</lname>
  <email>JLuser@bogus.com</email>
  <address>
   <street>Washington st.</street>
   <city>Old Creek</city>
   <country>The US</country>
   <bogus>bleargh</bogus>
  </address>
  <phones>
   <phone type="home">123-456-7890</phone>
   <phone type="office">663-486-7890</phone>
   <phone type="fax">663-486-7000</phone>
  </phones>
 </person>
 <person>
  <fname>John</fname>
  <lname>Other</lname>
  <email>JOther@silly.com</email>
  <address>
   <street>Grant's st.</street>
   <city>New Creek</city>
   <country>Canada</country>
   <bogus>sdrysdfgtyh degtrhy <foo>degtrhy werthy</foo>werthy drthyu</
+bogus>
  </address>
  <phones>
   <phone type="office">663-486-7891</phone>
  </phones>
 </person>
</doc>
*END*

%rules = (
    _default => 'content',
    bogus => undef, # means "ignore"
    address => sub {address => "$_[1]->{street}, $_[1]->{city} ($_[1]-
+>{country})"},
    person => sub {
        '@person' => "$_[1]->{lname}, $_[1]->{fname}\n<$_[1]->{email}>
+\n$_[1]->{address}"
    },
    doc => sub { join "\n\n", @{$_[1]->{person}} },
);
# $parser->parse() will return a single string containin the addresses
+ 
# in plain text format

%rules = (
    _default => 'content',
#    bogus => sub {}, # means "returns no value. The subtags ARE proce
+ssed.
    bogus => undef, # means "ignore". The subtags ARE NOT processed.
    address => 'no content',
    person => 'no content array',
    doc => sub {$_[1]->{person}}, #'pass no content',
    foo => sub {print "FOOOOOOOO\n"},
);
# returns a simplified data structure kinda similar to XML::Simple

my $parser = new XML::Rules (
    rules => [
        _default => sub {$_[0] => $_[1]->{_content}},
        'fname,lname' => sub {$_[0] => $_[1]->{_content}},
        bogus => undef,
        address => sub {address => "$_[1]->{street}, $_[1]->{city} ($_
+[1]->{country})"},
        phone => sub {$_[1]->{type} => $_[1]->{_content}},
            # let's use the "type" attribute as the key and the conten
+t as the value
        phones => sub {delete $_[1]->{_content}; %{$_[1]}},
            # remove the text content and pass along the type => conte
+nt from the child nodes
        person => sub { # lets print the values, all the data is readi
+ly available in the attributes
            print "$_[1]->{lname}, $_[1]->{fname} <$_[1]->{email}>\n";
            print "Home phone: $_[1]->{home}\n" if $_[1]->{home};
            print "Office phone: $_[1]->{office}\n" if $_[1]->{office}
+;
            print "Fax: $_[1]->{fax}\n" if $_[1]->{fax};
            print "$_[1]->{address}\n\n";
            return; # the <person> tag is processed, no need to rememb
+er what it contained
        },
    ]
);
# prints the addresses, returns nothing
[download]

As you can see the rules applied to the parsed tags are basicaly of two types. Either they specify what data gets passed to the parent tag's rule and how or they do something with the attributes of the tag and the data returned by the rules of subtags. You can of course do both in your rules. For example if the XML looked like this:

<doc>
 <person>
  <fname>Jane</fname>
  <lname>Luser</lname>
  <email>JLuser@bogus.com</email>
  <address>
   <street>Washington st.</street>
   <city>Old Creek</city>
   <country>The US</country>
   <bogus>bleargh</bogus>
  </address>
  <phones>
   <phone type="home">123-456-7890</phone>
   <phone type="office">663-486-7890</phone>
   <phone type="fax">663-486-7000</phone>
  </phones>
 </person>
 <person>
  <fname>John</fname>
  <lname>Other</lname>
  <email>JOther@silly.com</email>
  <address id="12345"/>
  <phones>
   <phone type="office">663-486-7891</phone>
  </phones>
 </person>
</doc>
[download]

You might use a subroutine like this for the <address> tag:

sub {
 if (exists $_[1]->{id} and $_[1]->{id}+0 > 0) {
  $get_addr->execute($_[1]->{id});
  my $result = $get_addr->fetchall_arrayref();
  my ($street, $sity, $country) = ( $result->[0][0], $result->[0][1], 
+$result->[0][2]);
  return address => "$_[1]->{street}, $_[1]->{city} ($_[1]->{country})
+"
 } else {
  return address => "$_[1]->{street}, $_[1]->{city} ($_[1]->{country})
+"
 }
}
[download]

and proceed as if the data was directly in the XML in all cases.