XTM::topic - Topic Map management, Topic

  use XTM::topic;

  my $t = new XTM::topic;
  ...
  print join (",", @{$t->occurrences()});
  print "bliss and happiness" if $t->has_instanceOf ('t-billionair');

  # now this time I am providing the id myself
  my $t2 = new XTM::topic (id => '1234');

  # there is also a cheap way to populate the topic with a default
  my $t3 = new XTM::topic (id => '1234', populate => \&XTM::topic::default_populate);

  # see XTM::generic for more methods

This package provides the primitive class Topic for Topic Maps.

The constructor expects a hash with following (optional) fields: a topic id (unique in the map in use), if not given, it will be generated a code reference to a subroutine populating the topic. There are the following predefined subroutines:

default_populate

This routine expects as first parameter a CWXTM::topic-blessed object and fills in the PSI topic as 'instanceOf', global scope where appropriate. It also generates in a fairly ad-hoc manner a 'baseName' from the topic id (substituting '-' by ' ').

  $t = new XTM::topic ('id' => 'x123');

Following accessor methods are available via XTM::generic (see that package how to set/add values):

baseNames:

@{ $t->baseNames} returns list reference of XTM::baseName nodes.

instanceOfs:

@{ $t->instanceOfs} returns list reference of XTM::instanceOf nodes.

subjectIdentity:

$t->subjectIdentity returns a XTM::subjectIdentity node

Other methods are:

id:

print $t->id $t->id (x123); returns the id of the topic. If provided with a non-empty scalar parameter, this value will be used to change the id.

occurrences:

@{ $t->occurrences } $t->occurrences ( $coderef ) $t->occurrences ( $arrayref ) returns the occurrences of the topic as a list reference. If provided with a CODEREF parameter, this subroutine will be used to filter the occurrences. If provided with a ARRAYREF parameter, this will be used as new value.

map:

$t->map $t->map ( $newmap ) is an accessor method for the CWmap component.

has_instanceOf:

$t->has_instanceOf ( $type_topic_id ) returns true if the topic is a direct subtype of a topic specified as CWtid for the only parameter. Example:

   print "bliss and happiness" if $t->has_instanceOf ('t-billionair');

add_defaults

$t->add_defaults This methods add default values according to the XTM standard. Specifically, it assures that

Every occurrence must have a type (XTM clause 3.9.1).

If a scope exists (in an occurrence or a baseName), then at least one reference must be there (XTM clause 3.3.1).

canonicalize

$t->canonicalize This method simplifies the topic by eliminating duplicates as prescribed in F.6.

connected:

@{ $t->connected } returns a list reference of all topic references mentioned in this topic. These references might be 'internal' or 'external' ones. Example:

   foreach (@{$t->connected}) {
     print "$t->id mentions $_\n";
   }

xml:

$t->xml ( $xmlwriter ) returns an XML representation of the topic. Example: CW$xmlwriter = new XML::Writer ... ... CW$t->xml($xmlwriter); # outputs all onto CW$xmlwriter

XTM, XTM::generic

Copyright 200[1-2], Robert Barta <rho@telecoma.net>, All rights reserved.

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself. http://www.perl.com/perl/misc/Artistic.html