XML::Handler::XMLWriter






XML::Handler::XMLWriter − a PerlSAX handler for writing
readable XML


 use XML::Parser::PerlSAX;
 use XML::Handler::XMLWriter;

      $my_handler = XML::Handler::XMLWriter‐>new( I<OPTIONS> );

      XML::Parser::PerlSAX‐>new‐>parse(Source => { SystemId => ’REC‐xml‐19980210.xml’ },
                                  Handler => $my_handler);

"XML::Handler::XMLWriter" is a PerlSAX handler for writing
readable XML (in contrast to Canonical XML, for example).
XML::Handler::XMLWriter can be used with a parser to
reformat XML, with XML::DOM or XML::Grove to write out XML,
or with other PerlSAX modules that generate events.

     "XML::Handler::XMLWriter" is intended to be used with
PerlSAX event generators and does not perform any checking
itself (for example, matching start and end element events).
If you want to generate XML directly from your Perl code,
use the XML::Writer module.  XML::Writer has an easy to use
interface and performs many checks to make sure that the XML
you generate is well−formed.

     "XML::Handler::XMLWriter" is a subclass of
"XML::Handler::Subs".  "XML::Handler::XMLWriter" can be
further subclassed to alter it’s behavior or to add element‐
specific handling.  In the subclass, each time an element
starts, a method by that name prefixed with ‘s_’ is called
with the element to be processed.  Each time an element
ends, a method with that name prefixed with ‘e_’ is called.
Any special characters in the element name are replaced by
underscores.  If there isn’t a start or end method for an
element, the default action is to write the start or end
tag.  Start and end methods can use the
‘"print_start_element()"’ and ‘"print_end_element()"’
methods to print start or end tags.  Subclasses can call the
‘"print()"’ method to write additional output.

     Subclassing XML::Handler::XMLWriter in this way is
similar to XML::Parser’s Stream style.

     XML::Handler::Subs maintains a stack of element names,
‘"$self−"{Names}’, and a stack of element nodes,
‘"$self−"{Nodes}>’ that can be used by subclasses.  The
current element is pushed on the stacks before calling an
element‐name start method and popped off the stacks after
calling the element‐name end method.

     See XML::Handler::Subs for additional methods.











                             ‐2‐


     In addition to the standard PerlSAX handler methods
(see PerlSAX for descriptions), XML::Handler::XMLWriter
supports the following methods:

new( OPTIONS )
    Creates and returns a new instance of
    XML::Handler::XMLWriter with the given OPTIONS.  Options
    may be changed at any time by modifying them directly in
    the hash returned.  OPTIONS can be a list of key, value
    pairs or a hash.  The following OPTIONS are supported:

    Output
        An IO::Handle or one of it’s subclasses (such as
        IO::File), if this parameter is not present and the
        AsString option is not used, the module will write
        to standard output.

    AsString
        Return the generated XML as a string from the
        ‘"parse()"’ method of the PerlSAX event generator.

    Newlines
        A true or false value; if this parameter is present
        and its value is true, then the module will insert
        an extra newline before the closing delimiter of
        start, end, and empty tags to guarantee that the
        document does not end up as a single, long line.  If
        the paramter is not present, the module will not
        insert the newlines.

    IsSGML
        A true or false value; if this parameter is present
        and its value is true, then the module will generate
        SGML rather than XML.

print_start_element($element)
    Print a start tag for ‘$element’.  This is the default
    action for the PerlSAX ‘"start_element()"’ handler, but
    subclasses may use this if they define a start method
    for an element.

print_end_element($element)
    Prints an end tag for ‘$element’.  This is the default
    action for the PerlSAX ‘"end_element()"’ handler, but
    subclasses may use this if they define a start method
    for an element.

print($output)
    Write ‘$output’ to Output and/or append it to the string
    to be returned.  Subclasses may use this to write
    additional output.












                             ‐3‐




•   An Elements option that provides finer control over
    newlines than the Newlines option, where you can choose
    before and after newline for element start and end tags.
    Inspired by the Python XMLWriter.

•   Support Doctype and XML declarations.

Ken MacLeod, ken@bitsko.slc.ut.us This module is partially
derived from XML::Writer by David Megginson.

perl(1), PerlSAX.pod(3)