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YAML::Node

Section: User Contributed Perl Documentation (3)
Updated: 2010-01-02
Index

NAME

YAML::Node - A generic data node that encapsulates YAML information

SYNOPSIS

    use YAML;    use YAML::Node;        my $ynode = YAML::Node->new({}, 'ingerson.com/fruit');    %$ynode = qw(orange orange apple red grape green);    print Dump $ynode;

yields:

    --- !ingerson.com/fruit    orange: orange    apple: red    grape: green

DESCRIPTION

A generic node in YAML is similar to a plain hash, array, or scalar nodein Perl except that it must also keep track of its type. The type is aURI called the YAML type tag.

YAML::Node is a class for generating and manipulating these containers.A YAML node (or ynode) is a tied hash, array or scalar. In most ways itbehaves just like the plain thing. But you can assign and retrieve andYAML type tag URI to it. For the hash flavor, you can also assign theorder that the keys will be retrieved in. By default a ynode will offerits keys in the same order that they were assigned.

YAML::Node has a class method call new() that will return a ynode. Youpass it a regular node and an optional type tag. After that you canuse it like a normal Perl node, but when you YAML::Dump it, the magicalproperties will be honored.

This is how you can control the sort order of hash keys during a YAMLserialization. By default, YAML sorts keys alphabetically. But noticein the above example that the keys were Dumped in the same order theywere assigned.

YAML::Node exports a function called ynode(). This function returns the tied object so that you can call special methods on it like ->keys().

keys() works like this:

    use YAML;    use YAML::Node;        %$node = qw(orange orange apple red grape green);    $ynode = YAML::Node->new($node);    ynode($ynode)->keys(['grape', 'apple']);    print Dump $ynode;

produces:

    ---    grape: green    apple: red

It tells the ynode which keys and what order to use.

ynodes will play a very important role in how programs use YAML. Theyare the foundation of how a Perl class can marshall the Loading andDumping of its objects.

The upcoming versions of YAML.pm will have much more information on this.

AUTHOR

Ingy dA~Xt Net <ingyAATTcpan.org>

COPYRIGHT

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

See <http://www.perl.com/perl/misc/Artistic.html>

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