What happens when you set a value:

$xml->{root}{foo} = 'simple value' ;

Here foo will be a normal argument/attribute value, and will generate this XML data:

<root foo="simple value"/>

But if you insert some tag or lines in the values by default XML::Smart will convert it to a node content:

$xml->{root}{foo} = "line0\nlien1\nline2\n" ;

And will generate that XML data:

<root>
<foo>line0
lien1
line2
</foo>
</root>

But what you can do if you want to force some type, let's say, have a node content with a simple value:

$xml->{root}{foo} = 'simple value' ;
$xml->{root}{foo}->set_node(1) ;

And will generate that XML data:

<root>
  <foo>simple value</foo>
</root>

Multiple contents:

When you have interpolated content/data you need to work in a different. Let's say that you load this XML data:

<root>
content0
<tag1 arg="1"/>
content1
</root>

If you access directly the root key as string you will get all the content parts grouped. So, this code:

my $xml = new XML::Smart(q`
<root>
content0
<tag1 arg="1"/>
content1
</root>
`,'smart') ;

print "#$xml->{root}#" ;

Will print that:

#
content0

content1
#

To access each part of the content independently you should use an array that receive the method content():

my @content = $xml->{root}->content ;

print "#$content[0]#\n" ;

And this will print that:

#
content0
#

Now to set the multiple content values you should use the method content() with 2 arguments:

$xml->{root}->content(0,'new content') ;

And now the XML data produced will be:

<root>new content<tag1 arg="1"/>
content1
</root>

If you use the method content() with only one argument it will remove all the multiple contents and will set the new value in the place of the 1st content.

Forcing nodes/tags and arguments/attributes to lowercase or upercase:

## For lower case:
my $xml = new XML::Smart( 'some.xml' ,
lowtag => 1 ,
lowarg => 1 ,
) ;

## For uper case:

my $xml = new XML::Smart( 'some.xml' ,
upertag => 1 ,
uperarg => 1 ,
) ;

Loading arguments without values (flags) as a TRUE boolean:

** Note, this option will work only when the XML is parsed by XML::Smart::HTMLParser, since only it accept arguments without values!

my $xml = new XML::Smart(
'<root><foo arg1="" flag></root>' ,
'XML::Smart::HTMLParser' ,
arg_single => 1 ,
) ;

Here's the tree of the example above:

'root' => {
            'foo' => {
                       'flag' => 1,
                       'arg1' => ''
                     },
          },

Customizing the parse events:

XML::Smart can redirect the parsing process to personalized functions:

my $xml = XML::Smart->new( 'some.xml' ,
on_start => \&on_start ,
on_char  => \&on_char ,
on_end   => \&on_end ,
) ;

sub on_start {
  my ( $tag , $pointer , $pointer_back ) = @_ ;
  $pointer->{$tag}{type_user} = 1 if $tag =~ /(?:name|age)/ ;
}
sub on_char {
  my ( $tag , $pointer , $pointer_back , $content) = @_ ;
  $$content =~ s/\s+/ /gs ;
}

sub on_end {
  my ( $tag , $pointer , $pointer_back ) = @_ ;
  $pointer->{$tag}{type_extra} = 1 if $tag =~ /(?:more|tel|address)/ ;
}