1YAML::Node(3) User Contributed Perl Documentation YAML::Node(3)
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6 YAML::Node - A generic data node that encapsulates YAML information
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9 use YAML;
10 use YAML::Node;
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12 my $ynode = YAML::Node->new({}, 'ingerson.com/fruit');
13 %$ynode = qw(orange orange apple red grape green);
14 print Dump $ynode;
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16 yields:
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18 --- !ingerson.com/fruit
19 orange: orange
20 apple: red
21 grape: green
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24 A generic node in YAML is similar to a plain hash, array, or scalar
25 node in Perl except that it must also keep track of its type. The type
26 is a URI called the YAML type tag.
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28 YAML::Node is a class for generating and manipulating these containers.
29 A YAML node (or ynode) is a tied hash, array or scalar. In most ways it
30 behaves just like the plain thing. But you can assign and retrieve and
31 YAML type tag URI to it. For the hash flavor, you can also assign the
32 order that the keys will be retrieved in. By default a ynode will offer
33 its keys in the same order that they were assigned.
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35 YAML::Node has a class method call new() that will return a ynode. You
36 pass it a regular node and an optional type tag. After that you can use
37 it like a normal Perl node, but when you YAML::Dump it, the magical
38 properties will be honored.
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40 This is how you can control the sort order of hash keys during a YAML
41 serialization. By default, YAML sorts keys alphabetically. But notice
42 in the above example that the keys were Dumped in the same order they
43 were assigned.
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45 YAML::Node exports a function called ynode(). This function returns the
46 tied object so that you can call special methods on it like ->keys().
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48 keys() works like this:
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50 use YAML;
51 use YAML::Node;
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53 %$node = qw(orange orange apple red grape green);
54 $ynode = YAML::Node->new($node);
55 ynode($ynode)->keys(['grape', 'apple']);
56 print Dump $ynode;
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58 produces:
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60 ---
61 grape: green
62 apple: red
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64 It tells the ynode which keys and what order to use.
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66 ynodes will play a very important role in how programs use YAML. They
67 are the foundation of how a Perl class can marshall the Loading and
68 Dumping of its objects.
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70 The upcoming versions of YAML.pm will have much more information on
71 this.
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74 Ingy doet Net <ingy@cpan.org>
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77 Copyright (c) 2006, 2011-2012. Ingy doet Net. All rights reserved.
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79 Copyright (c) 2002. Brian Ingerson. All rights reserved.
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81 This program is free software; you can redistribute it and/or modify it
82 under the same terms as Perl itself.
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84 See <http://www.perl.com/perl/misc/Artistic.html>
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87 Hey! The above document had some coding errors, which are explained
88 below:
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90 Around line 296:
91 Non-ASCII character seen before =encoding in 'doet'. Assuming UTF-8
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95perl v5.16.3 2012-07-13 YAML::Node(3)