1Algorithm::Dependency::USsoeurrcCeo(n3t)ributed Perl DocAulmgeonrtiatthimo:n:Dependency::Source(3)
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NAME

6       Algorithm::Dependency::Source - Implements a source of heirachy items
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DESCRIPTION

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

16   new @arguments
17       Although you cannot directly use the "new" constructor for
18       "Algorithm::Dependency::Source", it will work the same in all
19       subclasses.
20
21       The constructor takes zero or more subclass specific arguments to
22       define the location of the source of the items, and returns a new
23       object. Alrough it may check that the arguments you passed are valid,
24       the source will usually NOT actually load the items from the source,
25       instead defering the loading until you need to use the items.
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27       Returns a new object on success, or "undef" on error.
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29   load
30       The "load" method is the public method used to actually load the items
31       from their storage location into the the source object. The method will
32       automatically called, as needed, in most circumstances. You would
33       generally only want to use "load" manually if you think there may be
34       some uncertainty that the source will load correctly, and want to check
35       it will work.
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37       Returns true if the items are loaded successfully, or "undef" on error.
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39   item $name
40       The "item" method fetches and returns the item object specified by the
41       name argument.
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43       Returns an Algorithm::Dependency::Item object on success, or "undef" if
44       the named item does not exist in the source.
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46   items
47       The "items" method returns, as a list of objects, all of the items
48       contained in the source. The item objects will be returned in the same
49       order as that in the storage location.
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51       Returns a list of Algorithm::Dependency::Item objects on success, or
52       "undef" on error.
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54   missing_dependencies
55       By default, we are leniant with missing dependencies if the item is
56       neved used. For systems where having a missing dependency can be very
57       bad, the "missing_dependencies" method checks all Items to make sure
58       their dependencies exist.
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60       If there are any missing dependencies, returns a reference to an array
61       of their ids. If there are no missing dependencies, returns 0. Returns
62       "undef" on error.
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EXTENDING

65       "Algorithm::Dependency::Source" itself is a fairly thin module, and it
66       is intended that you will probably need to extend it to be able to
67       extract item data from whatever location you have stored them.
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69       This is usually a fairly simple two step process.
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71       Overload the "new" method.
72           Assuming your subclass takes some form or argument on creation, you
73           will need to overload the "new" method to accept the arguments,
74           validate them, and store them in the source object.
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76       Define the method "_load_item_list".
77           Leaving our parent's "load" method to take care of conflict,
78           errors, and whatever, the "_load_item_list" method is used to
79           simply create a list of Algorithm::Dependency::Item objects from
80           wherever you store the item, and return them as a list.
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82       Having completed these two things, your subclass should be completed.
83       For an example of the code, have a look at the source for the simple
84       subclass Algorithm::Dependency::Source::File.
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SUPPORT

87       For general comments, contact the author.
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89       To file a bug against this module, in a way you can keep track of, see
90       the CPAN bug tracking system.
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92       http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Algorithm-Dependency
93       <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Algorithm-Dependency>
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AUTHOR

96       Adam Kennedy <adamk@cpan.org>
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SEE ALSO

99       Algorithm::Dependency, Algorithm::Dependency::Source::File
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102       Copyright 2003 - 2009 Adam Kennedy.
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104       This program is free software; you can redistribute it and/or modify it
105       under the same terms as Perl itself.
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107       The full text of the license can be found in the LICENSE file included
108       with this module.
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112perl v5.12.0                      2009-04-14  Algorithm::Dependency::Source(3)
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