oracular (3) Algorithm::Dependency::Source.3pm.gz

Provided by: libalgorithm-dependency-perl_1.110-1.3_all bug

NAME
       Algorithm::Dependency::Source - Implements a source of heirachy items


DESCRIPTION
       The Algorithm::Dependency::Source class provides an abstract parent class for implementing sources for
       the heirachy data the algorithm will use. For an example of an implementation of this, see
       Algorithm::Dependency::Source::File, which is bundled with the main Algorithm::Dependency package.


METHODS
   new @arguments
       Although you cannot directly use the "new" constructor for "Algorithm::Dependency::Source", it will work
       the same in all subclasses.

       The constructor takes zero or more subclass specific arguments to define the location of the source of
       the items, and returns a new object. Alrough it may check that the arguments you passed are valid, the
       source will usually NOT actually load the items from the source, instead defering the loading until you
       need to use the items.

       Returns a new object on success, or "undef" on error.

   load
       The "load" method is the public method used to actually load the items from their storage location into
       the the source object. The method will automatically called, as needed, in most circumstances. You would
       generally only want to use "load" manually if you think there may be some uncertainty that the source
       will load correctly, and want to check it will work.

       Returns true if the items are loaded successfully, or "undef" on error.

   item $name
       The "item" method fetches and returns the item object specified by the name argument.

       Returns an Algorithm::Dependency::Item object on success, or "undef" if the named item does not exist in
       the source.

   items
       The "items" method returns, as a list of objects, all of the items contained in the source. The item
       objects will be returned in the same order as that in the storage location.

       Returns a list of Algorithm::Dependency::Item objects on success, or "undef" on error.

   missing_dependencies
       By default, we are leniant with missing dependencies if the item is neved used. For systems where having
       a missing dependency can be very bad, the "missing_dependencies" method checks all Items to make sure
       their dependencies exist.

       If there are any missing dependencies, returns a reference to an array of their ids. If there are no
       missing dependencies, returns 0. Returns "undef" on error.


EXTENDING
       "Algorithm::Dependency::Source" itself is a fairly thin module, and it is intended that you will probably
       need to extend it to be able to extract item data from whatever location you have stored them.

       This is usually a fairly simple two step process.

       Overload the "new" method.
           Assuming your subclass takes some form or argument on creation, you will need to overload the "new"
           method to accept the arguments, validate them, and store them in the source object.

       Define the method "_load_item_list".
           Leaving our parent's "load" method to take care of conflict, errors, and whatever, the
           "_load_item_list" method is used to simply create a list of Algorithm::Dependency::Item objects from
           wherever you store the item, and return them as a list.

       Having completed these two things, your subclass should be completed. For an example of the code, have a
       look at the source for the simple subclass Algorithm::Dependency::Source::File.


SUPPORT
       For general comments, contact the author.

       To file a bug against this module, in a way you can keep track of, see the CPAN bug tracking system.

       <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Algorithm-Dependency>


AUTHOR
       Adam Kennedy <adamk@cpan.org>


SEE ALSO
       Algorithm::Dependency, Algorithm::Dependency::Source::File


       Copyright 2003 - 2009 Adam Kennedy.

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

       The full text of the license can be found in the LICENSE file included with this module.