Provided by: libconfig-model-perl_2.047-1_all bug

NAME

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

VERSION

       version 2.047

SYNOPSIS

        use Config::Model;
        use Log::Log4perl qw(:easy);
        Log::Log4perl->easy_init($WARN);

        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

        $root->load( step => 'master_switch=cX' );
        print "Visible elements: ",join(' ',$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

        $root->load( step => 'master_switch=cY' );
        print "a_warped_node class: ",$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 will specify one (or several) leaf in the configuration tree that will
       trigger 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" will create 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
        experience
        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" will try 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
           will be 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" will create a new object of the
               type specified by this parameter:

                 XZ => { config_class_name => 'SlaveZ' }

               If you pass an array ref, the array will contain the class name and constructor
               arguments :

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

       experience
               Switch the experience of the slot when the object is warped in.

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
         (
          experience => [ bar => 'advanced'] ,
          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" will not be available. Trying to access bar
           will raise an exception.

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

       •   Then, if "tree_macro" is changed from "XX" to "XY", "bar" will refer to a brand new
           "ClassY" object. But in this case, the object will be initialized with most if not all
           the attributes of "ClassX". This copy will be 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) 2013 by Dominique Dumont.

       This is free software, licensed under:

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