algorithm::dependency::source::file(3pm) [debian man page]

Algorithm::Dependency::Source::File(3pm)		User Contributed Perl Documentation		  Algorithm::Dependency::Source::File(3pm)

NAME

       Algorithm::Dependency::Source::File - File source for dependency heirachys

DESCRIPTION

       Algorithm::Dependency::Source::File implements a source where the items are stored in a flat file or a relatively simple format.

   File Format
       The file should be an ordinary text file, consisting of a series of lines, with each line completely containing the information for a
       single item.  Blank lines, or lines beginning with the hash character '#' will be ignored as comments.

       For a single item line, only word characters will be used. A 'word character' consists of all letters and numbers, and the underscore '_'
       character.  Anything that is not a word character will be assumed to be a seperator.

       The first word will be used as the name or id of the item, and any further words in the line will be used as other items that this one
       depends on. For example, all of the following are legal.

	 # A single item with no dependencies
	 Foo

	 # Another item that depends on the first one
	 Bar Foo

	 # Depending on multiple others
	 Bin Foo Bar

	 # We can use different seperators
	 One:Two|Three-Four+Five=Six Seven

	 # We can also use multiple non-word characters as seperators
	 This&*&^*&File:  is& & & :::REALLY()Neat

       From the examples above, it should be easy to create your own files.

METHODS

       This documents the methods differing from the ordinary Algorithm::Dependency::Source methods.

   new $filename
       When constructing a new Algorithm::Dependency::Source::File object, an argument should be provided of the name of the file to use. The
       constructor will check that the file exists, and is readable, returning "undef" otherwise.

SUPPORT

       To file a bug against this module, use the CPAN bug tracking system

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

       For other comments, contact the author.

AUTHOR

       Adam Kennedy <adamk@cpan.org>

SEE ALSO

       Algorithm::Dependency

COPYRIGHT

       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.

perl v5.12.4							    2009-04-14				  Algorithm::Dependency::Source::File(3pm)

Algorithm::Dependency::Source(3pm)			User Contributed Perl Documentation			Algorithm::Dependency::Source(3pm)

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 <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

       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.

perl v5.12.4							    2009-04-14					Algorithm::Dependency::Source(3pm)