NAME¶

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

VERSION¶

version 2.154

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/} ]
    );
 }
 $model->create_config_class(
    name => "MyClass",
    element => [
        master_switch => {
            type       => 'leaf',
            value_type => 'enum',
            choice     => [qw/cX cY/]
        },
        'a_warped_node' => {
            type   => 'warped_node',
            warp => }
               follow => { ms => '! master_switch' },
               rules  => [
                   '$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¶

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¶

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) 2005-2022 by Dominique Dumont.

This is free software, licensed under:

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