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graph::reader::xml(3pm) [debian man page]

Graph::Reader::XML(3pm) 				User Contributed Perl Documentation				   Graph::Reader::XML(3pm)

NAME
Graph::Reader::XML - class for reading a Graph instance from XML SYNOPSIS
use Graph::Reader::XML; use Graph; $reader = Graph::Reader::XML->new(); $graph = $reader->read_graph('mygraph.xml'); DESCRIPTION
Graph::Reader::XML is a perl class used to read a directed graph stored as XML, and return an instance of the Graph class. The XML format is designed to support the Graph classes: it can be used to represent a single graph with a collection of nodes, and edges between those nodes. The graph, nodes, and edges can all have attributes specified, Graph::Reader::XML is a subclass of Graph::Reader, which defines the generic interface for Graph reader classes. METHODS
new() Constructor - generate a new reader instance. $reader = Graph::Reader::XML->new(); This doesn't take any arguments. read_graph() Read a graph from a file: $graph = $reader->read_graph( $file ); The $file argument can be either a filename or a filehandle of a previously opened file. KNOWN BUGS
Attribute values must be scalar. If they're not, well, you're on your own. SEE ALSO
Graph::Reader The base class for Graph::Reader::XML. Graph::Writer::XML Used to serialise a Graph instance as XML. Graph Jarkko Hietaniemi's classes for representing directed graphs. AUTHOR
Neil Bowers <neil@bowers.com> COPYRIGHT
Copyright (c) 2001-2012, Neil Bowers. All rights reserved. Copyright (c) 2001, Canon Research Centre Europe. All rights reserved. This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself. perl v5.14.2 2012-02-14 Graph::Reader::XML(3pm)

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Graph::Reader(3pm)					User Contributed Perl Documentation					Graph::Reader(3pm)

NAME
Graph::Reader - base class for Graph file format readers SYNOPSIS
package Graph::Reader::MyFormat; use Graph::Reader; use vars qw(@ISA); @ISA = qw(Graph::Reader); sub _read_graph { my ($self, $graph, $FILE) = @_; # read $FILE and populate $graph } DESCRIPTION
Graph::Reader is a base class for Graph file format readers. A particular subclass of Graph::Reader will handle a specific file format, and generate a Graph, represented using Jarkko Hietaniemi's Graph class. You should never create an instance of this class yourself, it is only meant for subclassing. If you try to create an instance of Graph::Reader, the constructor will throw an exception. METHODS
new() Constructor - generate a new reader instance. This is a virtual method, or whatever the correct lingo is. You're not meant to call this on the base class, it is inherited by the subclasses. Ie if you do something like: $reader = Graph::Reader->new(); It will throw an exception. read_graph() Read a graph from the specified file: $graph = $reader->read_graph($file); The $file argument can either be a filename, or a filehandle for a previously opened file. SUBCLASSING
To create your own graph format reader, create a module which subclasses Graph::Reader. For example, suppose DGF is a directed graph format - create a Graph::Reader::DGF module, with the following structure: package Graph::Reader::DGF; use Graph::Reader; use vars qw(@ISA); @ISA = qw(Graph::Reader); sub _read_graph { my $self = shift; my $graph = shift; my $FILE = shift; while (<$FILE>) { } return 1; } 1; Note the leading underscore on the _read_graph() method. The base class provides the public method, and invokes the private method which you're expected to provide, as above. If you want to perform additional initialisation at construction time, you can provide an _init() method, which will be invoked by the base class's constructor. You should invoke the superclass's initialiser as well, as follows: sub _init { my $self = shift; $self->SUPER::_init(); # your initialisation here } Someone can then use your class as follows: use Graph::Reader::DGF; $reader = Graph::Reader::DGF->new(); $graph = $reader->read_graph('foo.dgf'); SEE ALSO
Graph Jarkko Hietaniemi's modules for representing directed graphs, available from CPAN under modules/by-module/Graph/ Algorithms in Perl This O'Reilly book has a chapter on directed graphs, which is based around Jarkko's modules. Graph::Reader::XML A simple subclass of this class for reading a simple XML format for directed graphs. Graph::Writer A baseclass for Graph file format writers. AUTHOR
Neil Bowers <neil@bowers.com> COPYRIGHT
Copyright (c) 2001-2012, Neil Bowers. All rights reserved. Copyright (c) 2001, Canon Research Centre Europe. All rights reserved. This script is free software; you can redistribute it and/or modify it under the same terms as Perl itself. perl v5.14.2 2012-02-14 Graph::Reader(3pm)
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