1Hierarchy(3) User Contributed Perl Documentation Hierarchy(3)
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6 Data::Hierarchy - Handle data in a hierarchical structure
7
9 my $tree = Data::Hierarchy->new();
10 $tree->store ('/', {access => 'all'});
11 $tree->store ('/private', {access => 'auth',
12 '.note' => 'this is private});
13 $info = $tree->get ('/private/somewhere/deep');
15 # return actual data points in list context
17 ($info, @fromwhere) = $tree->get ('/private/somewhere/deep');
18 my @items = $tree->find ('/', {access => qr/.*/});
20 # override all children
22 $tree->store ('/', {'.note' => undef}, {override_sticky_descendents => 1});
23
25 Data::Hierarchy provides a simple interface for manipulating
26 inheritable data attached to a hierarchical environment (like a
27 filesystem).
28 One use of Data::Hierarchy is to allow an application to annotate paths
30 in a real filesystem in a single compact data structure. However, the
31 hierarchy does not actually need to correspond to an actual filesystem.
32 Paths in a hierarchy are referred to in a Unix-like syntax; "/" is the
34 root "directory". (You can specify a different separator character than
35 the slash when you construct a Data::Hierarchy object.) With the
36 exception of the root path, paths should never contain trailing
37 slashes. You can associate properties, which are arbitrary name/value
38 pairs, with any path. (Properties cannot contain the undefined value.)
39 By default, properties are inherited by child paths: thus, if you store
40 some data at "/some/path":
41 $tree->store('/some/path', {color => 'red'});
43 you can fetch it again at a "/some/path/below/that":
45 print $tree->get('/some/path/below/that')->{'color'};
47 # prints red
48 On the other hand, properties whose names begin with dots are
50 uninherited, or "sticky":
51 $tree->store('/some/path', {'.color' => 'blue'});
53 print $tree->get('/some/path')->{'.color'}; # prints blue
54 print $tree->get('/some/path/below/that')->{'.color'}; # undefined
55 Note that you do not need to (and in fact, cannot) explicitly add
57 "files" or "directories" to the hierarchy; you simply add and delete
58 properties to paths.
59
61 Creates a new hierarchy object. Takes the following options:
62 sep The string used as a separator between path levels. Defaults to
64 '/'.
65
67 Instance Methods
68 "store $path, $properties, {%options}"
69 Given a path and a hash reference of properties, stores the
70 properties at the path.
71 Unless the "override_descendents" option is given with a false
73 value, it eliminates any non-sticky property in a descendent of
74 $path with the same name.
75 If the "override_sticky_descendents" option is given with a true
77 value, it eliminates any sticky property in a descendent of $path
78 with the same name. override it.
79 A value of undef removes that value; note, though, that if an
81 ancestor of $path defines that property, the ancestor's value will
82 be inherited there; that is, with:
83 $t->store('/a', {k => 'top'});
85 $t->store('/a/b', {k => 'bottom'});
86 $t->store('/a/b', {k => undef});
87 print $t->get('/a/b')->{'k'};
88 it will print 'top'.
90 "get $path, [$dont_clone]"
92 Given a path, looks up all of the properteies (sticky and not) and
93 returns them in a hash reference. The values are clones, unless
94 you pass a true value for $dont_clone.
95 If called in list context, returns that hash reference followed by
97 all of the ancestral paths of $path which contain non-sticky
98 properties (possibly including itself).
99 "find $path, $property_regexps"
101 Given a path and a hash reference of name/regular expression pairs,
102 returns a list of all paths which are descendents of $path
103 (including itself) and define at that path itself (not inherited)
104 all of the properties in the hash with values matching the given
105 regular expressions. (You may want to use "qr/.*/" to merely see
106 if it has any value defined there.) Properties can be sticky or
107 not.
108 "merge $other_hierarchy, $path"
110 Given a second Data::Hierarchy object and a path, copies all the
111 properties from the other object at $path or below into the
112 corresponding paths in the object this method is invoked on. All
113 properties from the object this is invoked on at $path or below are
114 erased first.
115 "to_relative $base_path"
117 Given a path which every element of the hierarchy must be contained
118 in, returns a special Data::Hierarchy::Relative object which
119 represents the hierarchy relative that path. The only thing you can
120 do with a Data::Hierarchy::Relative object is call
121 "to_absolute($new_base_path)" on it, which returns a new
122 Data::Hierarchy object at that base path. For example, if
123 everything in the hierarchy is rooted at "/home/super_project" and
124 it needs to be moved to "/home/awesome_project", you can do
125 $hierarchy = $hierarchy->to_relative('/home/super_project')->to_absolute('/home/awesome_project');
127 (Data::Hierarchy::Relative objects may be a more convenient
129 serialization format than Data::Hierarchy objects, if they are
130 tracking the state of some relocatable resource.)
131
133 Chia-liang Kao <clkao@clkao.org> David Glasser <glasser@mit.edu>
134
136 Copyright 2003-2006 by Chia-liang Kao <clkao@clkao.org>.
137 This program is free software; you can redistribute it and/or modify it
139 under the same terms as Perl itself.
140 See <http://www.perl.com/perl/misc/Artistic.html>
142perl v5.28.1 2006-11-05 Hierarchy(3)