Provided by: libconfig-model-perl_2.117-1_all bug

NAME

       Config::Model::WarpedNode - Node that change config class properties

VERSION

       version 2.117

SYNOPSIS

        use Config::Model;

        my $model = Config::Model->new;
        foreach (qw/X Y/) {
           $model->create_config_class(
               name    => "Class$_",
               element => [ foo => {qw/type leaf value_type string/} ]
           );
        }
        $model->create_config_class(
           name => "MyClass",

           element => [
               master_switch => {
                   type       => 'leaf',
                   value_type => 'enum',
                   choice     => [qw/cX cY/]
               },

               'a_warped_node' => {
                   type   => 'warped_node',
                   follow => { ms => '! master_switch' },
                   rules  => [
                       '$ms eq "cX"' => { config_class_name => 'ClassX' },
                       '$ms eq "cY"' => { config_class_name => 'ClassY' },
                   ]
               },

           ],
        );

        my $inst = $model->instance(root_class_name => 'MyClass' );
        my $root = $inst->config_root ;

        print "Visible elements: ",join(' ',$root->get_element_name),"\n" ;
        # Visible elements: master_switch

        $root->load( steps => 'master_switch=cX' );
        print "Visible elements: ",join(' ',$root->get_element_name),"\n" ;
        # Visible elements: master_switch a_warped_node

        my $node = $root->grab('a_warped_node') ;
        print "a_warped_node class: ",$node->config_class_name,"\n" ;
        # a_warped_node class: ClassX

        $root->load( steps => 'master_switch=cY' );
        print "a_warped_node class: ",$node->config_class_name,"\n" ;
        # a_warped_node class: ClassY

DESCRIPTION

       This class provides a way to change dynamically the configuration class (or some other
       properties) of a node. The changes are done according to the model declaration.

       This declaration specifies one (or several) leaf in the configuration tree that triggers
       the actual property change of the warped node. This leaf is also referred as warp master.

       When the warp master(s) value(s) changes, "WarpedNode" creates an instance of the new
       class required by the warp master.

       If the morph parameter is set, the values held by the old object are (if possible) copied
       to the new instance of the object using copy_from method.

       Warped node can alter the following properties:

        config_class_name
        level

Constructor

       "WarpedNode" should not be created directly.

Warped node model declaration

   Parameter overview
       A warped node must be declared with the following parameters:

       type
           Always set to "warped_node".

       follow
           Grab string leading to the "Config::Model::Value" warp master.  See "Warp follow
           argument" in Config::Model::Warper for details.

       morph
           boolean. If 1, "WarpedNode" tries to recursively copy the value from the old object to
           the new object using copy_from method.  When a copy is not possible, undef values are
           assigned to object elements.

       rules
           Hash or array ref that specify the property change rules according to the warp
           master(s) value(s).  See "Warp rules argument" in Config::Model::Warper for details on
           how to specify the warp master values (or combination of values).

   Effect declaration
       For a warped node, the effects are declared with these parameters:

       config_class_name
               When requested by the warp master,the "WarpedNode" creates a new object of the
               type specified by this parameter:

                 XZ => { config_class_name => 'SlaveZ' }

               Instead of a string, you can an array ref which contains the class name and
               constructor arguments :

                 XY  => { config_class_name => ['SlaveY', foo => 'bar' ], },

       class   Specify a Perl class to implement the above config class. This Perl Class must
               inherit Config::Model::Node.

Forwarded methods

       The following methods are forwarded to contained node:

       fetch_element config_class_name get_element_name has_element is_element_available
       element_type load fetch_element_value get_type get_cargo_type describe

Methods

   name
       Return the name of the node (even if warped out).

   is_accessible
       Returns true if the node hidden behind this warped node is accessible, i.e. the warp
       master have values so a node was warped in.

   get_actual_node
       Returns the node object hidden behind the warped node. Croaks if the node is not
       accessible.

   load_data ( hash_ref )
       Load configuration data with a hash ref. The hash ref key must match the available
       elements of the node carried by the warped node.

EXAMPLE

        $model ->create_config_class
         (
          element =>
           [
            tree_macro => { type => 'leaf',
                            value_type => 'enum',
                            choice     => [qw/XX XY XZ ZZ/]
                          },
            bar =>  {
                      type => 'warped_node',
                      follow => '! tree_macro',
                      morph => 1,
                      rules => [
                                XX => { config_class_name
                                          => [ 'ClassX', 'foo' ,'bar' ]}
                                XY => { config_class_name => 'ClassY'},
                                XZ => { config_class_name => 'ClassZ'}
                               ]
                    }
           ]
         );

       In the example above we see that:

       •   The 'bar' slot can refer to a "ClassX", "ClassZ" or "ClassY" object.

       •   The warper object is the "tree_macro" attribute of the root of the object tree.

       •   When "tree_macro" is set to "ZZ", "bar" is not available. Trying to access "bar"
           raises an exception.

       •   When "tree_macro" is changed from "ZZ" to "XX", "bar" refers to a brand new "ClassX"
           object constructed with "ClassX->new(foo => 'bar')"

       •   Then, if "tree_macro" is changed from "XX" to "XY", "bar" refers to a brand new
           "ClassY" object. But in this case, the object is initialized with most if not all the
           attributes of "ClassX". This copy is done whenever "tree_macro" is changed.

AUTHOR

       Dominique Dumont, (ddumont at cpan dot org)

SEE ALSO

       Config::Model::Instance, Config::Model, Config::Model::HashId, Config::Model::ListId,
       Config::Model::AnyThing, Config::Model::Warper, Config::Model::WarpedNode,
       Config::Model::Value

AUTHOR

       Dominique Dumont

COPYRIGHT AND LICENSE

       This software is Copyright (c) 2005-2018 by Dominique Dumont.

       This is free software, licensed under:

         The GNU Lesser General Public License, Version 2.1, February 1999