XML::Namespace(3) Simple support for XML Namespaces


Example 1: using XML::Namespace objects
use XML::Namespace;
my $xsd = XML::Namespace->new('http://www.w3.org/2001/XMLSchema#');
# explicit access via the uri() method
print $xsd->uri(); # http://www.w3.org/2001/XMLSchema#
print $xsd->uri('integer'); # http://www.w3.org/2001/XMLSchema#integer
# implicit access through AUTOLOAD method
print $xsd->integer; # http://www.w3.org/2001/XMLSchema#integer
Example 2: importing XML::Namespace objects
use XML::Namespace
xsd => 'http://www.w3.org/2001/XMLSchema#',
rdf => 'http://www.w3.org/1999/02/22-rdf-syntax-ns#';
# xsd and rdf are imported subroutines that return
# XML::Namespace objects which can be used as above
print xsd->uri('integer'); # http://www.w3.org/2001/XMLSchema#integer
print xsd->integer; # http://www.w3.org/2001/XMLSchema#integer


This module implements a simple object for representing XML Namespaces in Perl. It provides little more than some syntactic sugar for your Perl programs, saving you the bother of typing lots of long-winded URIs. It was inspired by the Class::RDF::NS module distributed as part of Class::RDF.

Using XML::Namespace Objects

First load the XML::Namespace module.

    use XML::Namespace;

Then create an XML::Namespace object.

    my $xsd = XML::Namespace->new('http://www.w3.org/2001/XMLSchema#');

Then use the uri() method to return an absolute URI from a relative path.

    print $xsd->uri('integer'); # http://www.w3.org/2001/XMLSchema#integer

Alternately, use the AUTOLOAD method to map method calls to the uri() method.

    print $xsd->integer;        # http://www.w3.org/2001/XMLSchema#integer

Importing XML::Namespace Objects

When you "use" the XML::Namespace module, you can specify a list of namespace definitions.

    use XML::Namespace
        xsd => 'http://www.w3.org/2001/XMLSchema#',
        rdf => 'http://www.w3.org/1999/02/22-rdf-syntax-ns#';

This defines the "xsd" and "rdf" subroutines and exports them into the calling package. The subroutines simply return XML::Namespace objects initialised with the relevant namespace URIs.

    print xsd->uri('integer');  # http://www.w3.org/2001/XMLSchema#integer
    print xsd->integer;         # http://www.w3.org/2001/XMLSchema#integer

Overloaded Stringification Method

The XML::Namespace module overloads the stringification operator to return the namespace URI.

    my $xsd = XML::Namespace->new('http://www.w3.org/2001/XMLSchema#');
    print $xsd;           # http://www.w3.org/2001/XMLSchema#



Constructor method which creates a new XML::Namespace object. It expects a single argument denoting the URI that the namespace is to represent.

    use XML::Namespace;
    my $xsd = XML::Namespace->new('http://www.w3.org/2001/XMLSchema#');


When called without arguments, this method returns the URI of the namespace object, as defined by the argument passed to the new() constructor method.

    $xsd->uri();          # http://www.w3.org/2001/XMLSchema#

An argument can be passed to indicate a path relative to the namespace URI. The method returns a simple concatenation of the namespace URI and the relative path argument.

    $xsd->uri('integer'); # http://www.w3.org/2001/XMLSchema#integer


This method is provided to work with the Exporter mechanism. It expects a list of "($name, $uri)" pairs as arguments. It creates XML::Namespace objects and accessor subroutines that are then exported to the caller's package.

Although not intended for manual invocation, there's nothing to stop you from doing it.

    use XML::Namespace;
    XML::Namespace->import( xsd => 'http://www.w3.org/2001/XMLSchema#' );
    xsd()->integer;   # http://www.w3.org/2001/XMLSchema#integer

Note that the parentheses are required when accessing this subroutine.

    xsd()->integer;     # Good 
    xsd->integer;       # Bad

Unlike those that are defined automatically by the Importer, Perl doesn't know anything about these subroutines at compile time. Without the parentheses, Perl will think you're trying to call the "integer" method on an unknown "xsd" package and you'll see an error like:

    Can't locate object method "integer" via package "xsd"

That's why it's better to define your namespaces when you load the XML::Namespace module.

    use XML::Namespace
        xsd => 'http://www.w3.org/2001/XMLSchema#';
    xsd->integer;       # Good


The module defines an AUTOLOAD method that maps all other method calls to the uri() method. Thus, the following return the same value.

    $xsd->uri('integer'); # http://www.w3.org/2001/XMLSchema#integer
    $xsd->integer;        # http://www.w3.org/2001/XMLSchema#integer


Andy Wardley <mailto:[email protected]>


This is version 0.02 of XML::Namespace.


Copyright (C) 2005 Andy Wardley. All Rights Reserved.

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.