XML::LibXML Processing Instructions

Synopsis

use XML::LibXML;
# Only methods specific to Processing Instruction nodes are listed here,
# see XML::LibXML::Node manpage for other methods

Description
Processing instructions are implemented with XML::LibXML with read and write access. The PI data is the PI without the PI target (as specified in XML 1.0 [17]) as a string. This string can be accessed with getData as implemented in Abstract Base Class of XML::LibXML Nodes.
The write access is aware about the fact, that many processing instructions have attribute like data. Therefore setData() provides besides the DOM spec conform Interface to pass a set of named parameter. So the code segment

my $pi = $dom->createProcessingInstruction("abc");
$pi->setData(foo=>'bar', foobar=>'foobar');
$dom->appendChild( $pi );

will result the following PI in the DOM:

<?abc foo="bar" foobar="foobar"?>

Which is how it is specified in the DOM specification. This three step interface creates temporary a node in perl space. This can be avoided while using the insertProcessingInstruction() method. Instead of the three calls described above, the call

$dom->insertProcessingInstruction("abc",'foo="bar" foobar="foobar"');

will have the same result as above.
XML::LibXML Processing Instructions's implementation of setData() documented below differs a bit from the standard version as available in Abstract Base Class of XML::LibXML Nodes:
setData 	

$pinode->setData( $data_string );
$pinode->setData( name=>string_value [...] );

This method allows one to change the content data of a PI. Additionally to the interface specified for DOM Level2, the method provides a named parameter interface to set the data. This parameter list is converted into a string before it is appended to the PI.