Writing XML¶

new([$params])

Create a new XML::Writer object:

  my $writer = XML::Writer->new(OUTPUT => $output, NEWLINES => 1);
    

Arguments are an anonymous hash array of parameters:

end()

Finish creating an XML document. This method will check that the document has exactly one document element, and that all start tags are closed:

  $writer->end();
    

If OUTPUT as been set to self, end() will return the generated document as well.

xmlDecl([$encoding, $standalone])

Add an XML declaration to the beginning of an XML document. The version will always be "1.0". If you provide a non-null encoding or standalone argument, its value will appear in the declaration (any non-null value for standalone except 'no' will automatically be converted to 'yes'). If not given here, the encoding will be taken from the ENCODING argument. Pass the empty string to suppress this behaviour.

  $writer->xmlDecl("UTF-8");
    

doctype($name, [$publicId, $systemId])

Add a DOCTYPE declaration to an XML document. The declaration must appear before the beginning of the root element. If you provide a publicId, you must provide a systemId as well, but you may provide just a system ID by passing 'undef' for the publicId.

  $writer->doctype("html");
    

comment($text)

Add a comment to an XML document. If the comment appears outside the document element (either before the first start tag or after the last end tag), the module will add a carriage return after it to improve readability. In data mode, comments will be treated as empty tags:

  $writer->comment("This is a comment");
    

pi($target [, $data])

Add a processing instruction to an XML document:

  $writer->pi('xml-stylesheet', 'href="style.css" type="text/css"');
    

If the processing instruction appears outside the document element (either before the first start tag or after the last end tag), the module will add a carriage return after it to improve readability.

The $target argument must be a single XML name. If you provide the $data argument, the module will insert its contents following the $target argument, separated by a single space.

startTag($name [, $aname1 => $value1, ...])

Add a start tag to an XML document. Any arguments after the element name are assumed to be name/value pairs for attributes: the module will escape all '&', '<', '>', and '"' characters in the attribute values using the predefined XML entities:

  $writer->startTag('doc', 'version' => '1.0',
                           'status' => 'draft',
                           'topic' => 'AT&T');
    

All start tags must eventually have matching end tags.

emptyTag($name [, $aname1 => $value1, ...])

Add an empty tag to an XML document. Any arguments after the element name are assumed to be name/value pairs for attributes (see startTag() for details):

  $writer->emptyTag('img', 'src' => 'portrait.jpg',
                           'alt' => 'Portrait of Emma.');
    

endTag([$name])

Add an end tag to an XML document. The end tag must match the closest open start tag, and there must be a matching and properly-nested end tag for every start tag:

  $writer->endTag('doc');
    

If the $name argument is omitted, then the module will automatically supply the name of the currently open element:

  $writer->startTag('p');
  $writer->endTag();
    

dataElement($name, $data [, $aname1 => $value1, ...])

Print an entire element containing only character data. This is equivalent to

  $writer->startTag($name [, $aname1 => $value1, ...]);
  $writer->characters($data);
  $writer->endTag($name);
    

characters($data)

Add character data to an XML document. All '<', '>', and '&' characters in the $data argument will automatically be escaped using the predefined XML entities:

  $writer->characters("Here is the formula: ");
  $writer->characters("a < 100 && a > 5");
    

You may invoke this method only within the document element (i.e. after the first start tag and before the last end tag).

In data mode, you must not use this method to add whitespace between elements.

raw($data)

Print data completely unquoted and unchecked to the XML document. For example raw('<') will print a literal < character. This necessarily bypasses all well-formedness checking, and is therefore only available in unsafe mode.

This can sometimes be useful for printing entities which are defined for your XML format but the module doesn't know about, for example &nbsp; for XHTML.

cdata($data)

As characters() but writes the data quoted in a CDATA section, that is, between <![CDATA[ and ]]>. If the data to be written itself contains ]]>, it will be written as several consecutive CDATA sections.

cdataElement($name, $data [, $aname1 => $value1, ...])

As dataElement() but the element content is written as one or more CDATA sections (see cdata()).

setOutput($output)

Set the current output destination, as in the OUTPUT parameter for the constructor.

getOutput()

Return the current output destination, as in the OUTPUT parameter for the constructor.

setDataMode($mode)

Enable or disable data mode, as in the DATA_MODE parameter for the constructor.

getDataMode()

Return the current data mode, as in the DATA_MODE parameter for the constructor.

setDataIndent($step)

Set the indent step for data mode, as in the DATA_INDENT parameter for the constructor.

getDataIndent()

Return the indent step for data mode, as in the DATA_INDENT parameter for the constructor.

Querying XML¶

in_element($name)

Return a true value if the most recent open element matches $name:

  if ($writer->in_element('dl')) {
    $writer->startTag('dt');
  } else {
    $writer->startTag('li');
  }
    

within_element($name)

Return a true value if any open element matches $name:

  if ($writer->within_element('body')) {
    $writer->startTag('h1');
  } else {
    $writer->startTag('title');
  }
    

current_element()

Return the name of the currently open element:

  my $name = $writer->current_element();
    

This is the equivalent of

  my $name = $writer->ancestor(0);
    

ancestor($n)

Return the name of the nth ancestor, where $n=0 for the current open element.

Additional Namespace Support¶

As of 0.510, these methods may be used while writing a document.

addPrefix($uri, $prefix)

Add a preferred mapping between a Namespace URI and a prefix. See also the PREFIX_MAP constructor parameter.

To set the default namespace, omit the $prefix parameter or set it to ''.

removePrefix($uri)

Remove a preferred mapping between a Namespace URI and a prefix.

forceNSDecl($uri)

Indicate that a namespace declaration for this URI should be included with the next element to be started.

PRINTING OUTPUT¶

If OUTPUT has been set to self and the object has been called in a string context, it'll return the xml document.

to_string

If OUTPUT has been set to self, calls an implicit end() on the document and prints it. Dies if OUTPUT has been set to anything else.