XML::SAX::DocumentLocator (3pm)

  my $locator = XML::SAX::DocumentLocator->new(
      sub { $object->get_public_id },
      sub { $object->get_system_id },
      sub { $reader->current_line },
      sub { $reader->current_column },
      sub { $reader->get_encoding },
      sub { $reader->get_xml_version },
  );

This module gives you a tied hash reference that calls the specified closures when asked for PublicId, SystemId, LineNumber and ColumnNumber.

It is useful for writing \s-1SAX\s0 Parsers so that you don't have to constantly update the line numbers in a hash reference on the object you pass to set_document_locator(). See the source code for XML::SAX::PurePerl for a usage example.

There is only 1 method: \*(C`new\*(C'. Simply pass it a list of closures that when called will return the PublicId, the SystemId, the LineNumber, the ColumnNumber, the Encoding and the XMLVersion respectively.

The closures are passed a single parameter, the key being requested. But you're free to ignore that.