Config::Model::Node(3pm)

NAME
Config::Model::Node - Class for configuration tree node

SYNOPSIS
 $model->create_config_class
  (
   name              => 'OneConfigClass',
   class_description => "OneConfigClass detailed description",

   element           => [
                          [qw/X Y Z/]
                          => {
                               type => 'leaf',
                               value_type => 'enum',
                               choice     => [qw/Av Bv Cv/]
                             }
                        ],

   experience        => [ Y => 'beginner',
                          X => 'master'
                        ],
   status            => [ X => 'deprecated' ],
   description       => [ X => 'X-ray description (can be long)' ],
   summary           => [ X => 'X-ray' ],

   accept            => [ { name_match => 'ip.*',
                            type => 'leaf',
                            value_type => 'uniline',
                            summary => 'ip address',
                          }
                        ]
  );

 my $instance = $model->instance (root_class_name => 'OneConfigClass',
                                  instance_name => 'test1');
 my $root_node = $instance -> config_root ;

DESCRIPTION
This class provides the nodes of a configuration tree. When created, a node object will get a set of rules that will define its properties within the configuration tree.

Each node contain a set of elements. An element can contain:

•   A leaf element implemented with Config::Model::Value. A leaf can be plain (unconstrained value) or be strongly typed (values are checked against a set of rules).

•   Another node.

•   A collection of items: a list element, implemented with Config::Model::ListId. Each item can be another node or a leaf.

•   A collection of identified items: a hash element, implemented with Config::Model::HashId. Each item can be another node or a leaf.

Configuration class declaration
A class declaration is made of the following parameters:

name
    Mandatory "string" parameter. This config class name can be used by a node element in another configuration class.

class_description
    Optional "string" parameter. This description will be used when generating user interfaces.

element
    Mandatory "list ref" of elements of the configuration class :

      element => [ foo => { type = 'leaf', ... },
                   bar => { type = 'leaf', ... }
                 ]

    Element names can be grouped to save typing:

      element => [ [qw/foo bar/] => { type = 'leaf', ... } ]

    See below for details on element declaration.

experience
    Optional "list ref" of the elements whose experience are different from default value ("beginner"). Possible values are "master", "advanced" and "beginner".

      experience   => [ Y => 'beginner',
                        [qw/foo bar/] => 'master'
                      ],

level
    Optional "list ref" of the elements whose level are different from default value ("normal"). Possible values are "important", "normal" or "hidden".

    The level is used to set how configuration data is presented to the user in browsing mode. "Important" elements will be shown to the user no matter what. "hidden" elements will be explained with the warp notion.

      level  => [ [qw/X Y/] => 'important' ]

status
    Optional "list ref" of the elements whose status are different from default value ("standard"). Possible values are "obsolete", "deprecated" or "standard".

    Using a deprecated element will issue a warning. Using an obsolete element will raise an exception (See Config::Model::Exception.

      status  => [ [qw/X Y/] => 'obsolete' ]

description
    Optional "list ref" of element description. These descriptions will be used when generating user interfaces.

description
    Optional "list ref" of element summary. These descriptions will be used when generating user interfaces or as comment when writing configuration files.

read_config
write_config
config_dir
    Parameters used to load on demand configuration data. See Config::Model::AutoRead for details.

accept
    Optional list of criteria to accept unknown parameters. Each criteria will have a list of specification that will enable "Config::Model" to create a model snippet for the unknown element.

    Example:

      accept =>      [
                        {
                                name_match => 'list.*',
                                type => 'list',
                                cargo => {
                                            type => 'leaf',
                                            value_type => 'string',
                                         } ,
                         },
                         {
                                name_match => 'str.*',
                                type => 'leaf',
                                value_type => 'uniline'
                         },
                      ]

    All "element" parameter and "name_match" can be used for "accept".

Element declaration

  Element type
Each element is declared with a list ref that contains all necessary information:

  element => [
               foo => { ... }
             ]

This most important information from this hash ref is the mandatory type parameter. The type type can be:

"node"
    The element is a simple node of a tree instanciated from a configuration class (declared with "create_config_class( ... )" in Config::Model). See "Node element".

"warped_node"
    The element is a node whose properties (mostly "config_class_name") can be changed (warped) according to the values of one or more leaf elements in the configuration tree. See Config::Model::WarpedNode for details.

"leaf"
    The element is a scalar value. See "Leaf element"

"hash"
    The element is a collection of nodes or values (default). Each element of this collection is identified by a string (Just like a regular hash, except that you can set up constraint of the keys). See "Hash element"

"list"
    The element is a collection of nodes or values (default). Each element of this collection is identified by an integer (Just like a regular perl array, except that you can set up constraint of the keys). See "List element"

"check_list"
    The element is a collection of values which are unique in the check_list. See CheckList.

  Node element
When declaring a "node" element, you must also provide a "config_class_name" parameter. For instance:

 $model ->create_config_class
   (
   name => "ClassWithOneNode",
   element => [
                the_node => {
                              type => 'node',
                              config_class_name => 'AnotherClass',
                            },
              ]
   ) ;

  Leaf element
When declaring a "leaf" element, you must also provide a "value_type" parameter. See Config::Model::Value for more details.

  Hash element
When declaring a "hash" element, you must also provide a "index_type" parameter.

You can also provide a "cargo_type" parameter set to "node" or "leaf" (default).

See Config::Model::HashId and Config::Model::AnyId for more details.

  List element
You can also provide a "cargo_type" parameter set to "node" or "leaf" (default).

See Config::Model::ListId and Config::Model::AnyId for more details.

Introspection methods

  name
Returns the location of the node, or its config class name (for root node).

  get_type
Returns "node".

  config_model
Returns the entire configuration model (Config::Model object).

  model
Returns the configuration model of this node (data structure).

  config_class_name
Returns the configuration class name of this node.

  instance
Returns the instance object containing this node. Inherited from Config::Model::AnyThing

  has_element ( element_name )
Returns 1 if the class model has the element declared or if the element name is matched by the optional "accept" parameter.

  find_element ( element_name , [ case => any ])
Returns $name if the class model has the element declared or if the element name is matched by the optional "accept" parameter.

If case is set to any, has_element will return the element name who match the passed name in a case-insensitive manner.

Returns empty if no matching element is found.

  searcher ()
Returns an object dedicated to search an element in the configuration model (respecting privilege level).

This method returns a Config::Model::Searcher object. See Config::Model::Searcher for details on how to handle a search.

This method is inherited from Config::Model::AnyThing.

  element_model ( element_name )
Returns model of the element.

  element_type ( element_name )
Returns the type (e.g. leaf, hash, list, checklist or node) of the element.

  element_name()
Returns the element name that contain this object. Inherited from Config::Model::AnyThing

  index_value()
See "index_value()" in Config::Model::AnyThing

  parent()
See "parent()" in Config::Model::AnyThing

  root()
See "root()" in Config::Model::AnyThing

  location()
See "location()" in Config::Model::AnyThing

Element property management

  get_element_name ( for => <experience>, ... )
Return all elements names available for "experience". If no experience is specified, will return all slots available at 'master' level (I.e all elements).

Optional paremeters are:

•   type: Returns only element of requested type (e.g. "list", "hash", "leaf",...). By default return elements of any type.

•   cargo_type: Returns only element which contain requested type. E.g. if "get_element_name" is called with "cargo_type => leaf", "get_element_name" will return simple leaf elements, but also hash or list element that contain leaf object. By default return elements of any type.

Returns an array in array context, and a string (e.g. "join(' ',@array)") in scalar context.

  next_element ( element_name, [ experience_index ] )
This method provides a way to iterate through the elements of a node.

Returns the next element name for a given experience (default "master"). Returns undef if no next element is available.

  previous_element ( element_name, [ experience_index ] )
This method provides a way to iterate through the elements of a node.

Returns the previous element name for a given experience (default "master"). Returns undef if no previous element is available.

  get_element_property ( element => ..., property => ... )
Retrieve a property of an element.

I.e. for a model :

  experience => [ X => 'master'],
  status     => [ X => 'deprecated' ]
  element    => [ X => { ... } ]

This call will return "deprecated":

  $node->get_element_property ( element => 'X', property => 'status' )

  set_element_property ( element => ..., property => ... )
Set a property of an element.

  reset_element_property ( element => ... )
Reset a property of an element according to the original model.

Information management

  fetch_element ( name => .. [ , user_experience => .. ] , [ check => ..] )
Fetch and returns an element from a node.

If user_experience is given, this method will check that the user has enough privilege to access the element. If not, a "RestrictedElement" exception will be raised.

check can be set to yes, no or skip

  fetch_element_value ( name => ... [ check => ...] )
Fetch and returns the value of a leaf element from a node.

If user_experience is given, this method will check that the user has enough privilege to access the element. If not, a "RestrictedElement" exception will be raised.

  store_element_value ( name, value )
Store a value in a leaf element from a node.

Can be invoked with named parameters (name, value, experience, check)

If user_experience is given, this method will check that the user has enough privilege to access the element. If not, a "RestrictedElement" exception will be raised.

  is_element_available( name => ..., experience => ... )
Returns 1 if the element "name" is available for the given "experience" ('beginner' by default) and if the element is not "hidden". Returns 0 otherwise.

As a syntactic sugar, this method can be called with only one parameter:

   is_element_available( 'element_name' ) ;

  accept_element( name )
Checks and returns the appropriate model of an acceptable element (be it explicetely declared, or part of an "accept" declaration). Returns undef if the element cannot be accepted.

  accept_regexp( name )
Returns the list of regular expressions used to check for acceptable parameters. Useful for diagnostics.

  element_exists( element_name )
Returns 1 if the element is known in the model.

  is_element_defined( element_name )
Returns 1 if the element is defined.

  grab(...)
See "grab(...)" in Config::Model::AnyThing.

  grab_value(...)
See "grab_value(...)" in Config::Model::AnyThing.

  grab_root()
See "grab_root()" in Config::Model::AnyThing.

  get( path [ custom | preset | standard | default ])
Get a value from a directory like path.

  set( path , value)
Set a value from a directory like path.

Serialisation

  load ( step => string [, experience => ... ] )
Load configuration data from the string into the node and its siblings.

This string follows the syntax defined in Config::Model::Loader. See "load ( ... )" in Config::Model::Loader for details on parameters. "experience" is 'master' by default.

This method can also be called with a single parameter:

  $node->load("some data:to be=loaded");

  load_data ( hash_ref, hash_ref,[ $check ])
Load configuration data with a hash ref (first parameter). The hash ref key must match the available elements of the node. The hash ref structure must match the structure of the configuration model.

The second parameter is optional and contains annotations for elements. A standard hash of hash (or list) may contain annotation only for leaf elements. In order to support annotation for nodes or other elements, hash keys can also contain annotations like "foo# foo note". Also the special key '__' will store the annotation in the containing object.

  dump_tree ( ... )
Dumps the configuration data of the node and its siblings into a string. See "dump_tree" in Config::Model::Dumper for parameter details.

This string follows the syntax defined in Config::Model::Loader. The string produced by "dump_tree" can be passed to "load".

  describe ( [ element => ... ] )
Provides a decription of the node elements or of one element.

  report ()
Provides a text report on the content of the configuration below this node.

  audit ()
Provides a text audit on the content of the configuration below this node. This audit will show only value different from their default value.

  copy_from ( another_node_object )
Copy configuration data from another node into this node and its siblings. The copy is made in a tolerant mode where invalid data are simply discarded.

Help management

  get_help ( [ [ description | summary ] => element_name ] )
If called without element, returns the description of the class (Stored in "class_description" attribute of a node declaration).

If called with an element name, returns the description of the element (Stored in "description" attribute of a node declaration).

If called with 2 argument, either return the "summary" or the "description" of the element.

Returns an empty string if no description was found.

  AutoRead nodes
As configuration model are getting bigger, the load time of a tree gets longer. The Config::Model::AutoRead class provides a way to load the configuration information only when needed.

TBD

AUTHOR
Dominique Dumont, (ddumont at cpan dot org)

SEE ALSO
Config::Model, Config::Model::Instance, Config::Model::HashId, Config::Model::ListId, Config::Model::CheckList, Config::Model::WarpedNode, Config::Model::Value