Config::Model::Node(3pm)				User Contributed Perl Documentation				  Config::Model::Node(3pm)

NAME

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

VERSION

       version 2.021

SYNOPSIS

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

	# define configuration tree object
	my $model = Config::Model->new;
	$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 => [
	       'ip.*' => {
		   type       => 'leaf',
		   value_type => 'uniline',
		   summary    => 'ip address',
	       }
	   ]
	);
	my $instance = $model->instance (root_class_name => 'OneConfigClass');
	my $root = $instance->config_root ;

	# X is not shown below because of its deprecated status
	print $root->describe,"
" ;
	# name	       value	    type	 comment
	# Y	       [undef]	    enum	 choice: Av Bv Cv
	# Z	       [undef]	    enum	 choice: Av Bv Cv

	# add some data
	$root->load( step => 'Y=Av' );

	# add some accepted element, ipA and ipB are created on the fly
	$root->load( step => q!ipA=192.168.1.0 ipB=192.168.1.1"! );

	# show also ip* element created in the last "load" call
	print $root->describe,"
" ;
	# name	       value	    type	 comment
	# Y	       Av	    enum	 choice: Av Bv Cv
	# Z	       [undef]	    enum	 choice: Av Bv Cv
	# ipA	       192.168.1.0  uniline
	# ipB	       192.168.1.1  uniline

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:

       o   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).

       o   Another node.

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

       o   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 (i.e. a regular expression to match ) 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 => [
	       'list.*' => {
		   type  => 'list',
		   cargo => {
		       type	  => 'leaf',
		       value_type => 'string',
		   },
	       },
	       'str.*' => {
		   type       => 'leaf',
		   value_type => 'uniline'
	       },
	     ]

	   All "element" parameters can be used in specifying accepted parameters.

	   The parameter "accept_after" to specify where to insert the accepted element.  This will not change much the behavior of the tree, but
	   it will help generate user interface easier to use.

	   Example:

	    element => [
	       'Bug' => { type => 'leaf', value_type => 'uniline' } ,
	    ]
	    accept => [
	       'Bug-.*' =>  {
		    value_type => 'uniline',
		    type => 'leaf'
		    accept_after => 'Bug' ,
	       }
	    ]

	   The model snippet above will ensure that "Bug-Debian" will be shown right after "bug".

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 instantiated 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 ( name => element_name, [ type => searched_type ] )
       Returns 1 if the class model has the element declared or if the element name is matched by the optional "accept" parameter. If "type" is
       specified, the element name must also match the type.

   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.

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

       This method returns a Config::Model::SearchElement object. See Config::Model::SearchElement 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 elements available at 'master' level
       (I.e all elements).

       Optional parameters are:

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

       o   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.

       o   check: "yes", "no" or "skip"

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

   children
       Like get_element_name without parameters. Returns the list of elements. This method is polymorphic for all non-leaf objects of the
       configuration tree.

   next_element ( ... )
       This method provides a way to iterate through the elements of a node.  Mandatory parameter is "name". Optional parameters are "experience"
       and "status".

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

   previous_element ( name => element_name, [ experience => min_experience ] )
       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 explicitly 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 => ..., mode => ... ,  check => ... , get_obj => 1|0, autoadd => 1|0)
       Get a value from a directory like path. If "get_obj" is 1, "get" will return leaf object instead of returning their value.

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

data modification
   migrate
       Force a read of the configuration and perform all changes regarding deprecated elements or values. Return 1 if data needs to be saved.

   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, [ $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.

   needs_save
       return 1 if one of the elements of the node's sub-tree has been modified.

Serialization
   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".

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

   describe ( [ element => ... ] )
       Provides a description 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.

   tree_searcher( type => ... )
       Returns an object able to search the configuration tree.  Parameters are :

       type
	   Where to perform the search. It can be "element", "value", "key", "summary", "description", "help" or "all".

       Typically, you will have to call "search" on this object.

       Returns a Config::Model::TreeSearcher object.

   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.

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

perl v5.14.2							    2012-11-09						  Config::Model::Node(3pm)