debian man page for config::model::searchelement

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

NAME
       Config::Model::SearchElement - Search an element in a configuration model

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    => "Foo",
	   element => [
	       [qw/foo bar/] => {
		   type       => 'leaf',
		   value_type => 'string'
	       },
	   ]
	);
	$model ->create_config_class (
	   name => "MyClass",

	   element => [

	       [qw/foo bar/] => {
		   type       => 'leaf',
		   value_type => 'string'
	       },
	       hash_of_nodes => {
		   type       => 'hash',     # hash id
		   index_type => 'string',
		   cargo      => {
		       type		 => 'node',
		       config_class_name => 'Foo'
		   },
	       },
	   ],
	) ;

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

	my $root = $inst->config_root ;

	# put data
	my $step = 'foo=FOO hash_of_nodes:fr foo=bonjour -
	  hash_of_nodes:en foo=hello ';
	$root->load( step => $step );

	# create searcher for manual search
	my $searcher = $root->searcher();

	# looking for foo element in the tree
	$searcher -> prepare (element => 'foo') ;
	my @next = $searcher->next_step() ;

	print "next possible steps: @next
";
	# next possible steps: foo hash_of_nodes

	# Looking for foo below hash_of_nodes
	$searcher->choose('hash_of_nodes') ;
	@next = $searcher->next_step() ;

	print "next possible steps: @next
";
	# next possible steps: en fr

	# Looking for foo below fr
	$searcher->choose('fr') ;
	@next = $searcher->next_step() ;

	print "next possible steps: @next
";
	# next possible steps: foo

	# last step
	$searcher->choose('foo') ;
	my $target = $searcher->current_object;

	print "Found '",$target->location,"'
";
	# Found 'hash_of_nodes:fr foo'

	# automatic search setup
	my $element_call_back = sub { return 'hash_of_nodes' ;} ;
	my $id_call_back      = sub { return 'en' ;} ;

	$searcher->reset ;
	$target = $searcher->auto_choose($element_call_back, $id_call_back) ;
	 print "Automatic search found '",$target->location,"'
";
	# Automatic search found 'hash_of_nodes:en foo'

DESCRIPTION
       This modules provides a way to search for a configuration element in a configuration tree by exploring the configuration model.

       For instance, suppose that you have a xorg.conf model and you know that you need to tune the "MergedXinerama" parameter, but you don't
       remember where is this parameter in the configuration tree. This module will guide you through the tree to the(s) node(s) that contain this
       parameter.

       This class should be invaluable to construct interactive user interfaces.

       This module provides 2 search modes:

       o   A manual search where you are guided step by step to the element you're looking for. At each step, the module will return you the
	   possible paths to choose from. The user will have to choose the correct path from the available paths. Most of the time, only one
	   possibility will be returned, so the user choice should be straightforward. In other case (more that one choice), the user will have to
	   decide the next step.

       o   An automatic search where you provide call-back that will resolve the ambiguities in case of multiple paths.

CONSTRUCTOR
       The constructor should be used only by Config::Model::Node.

Methods
   get_searchable_elements
       Return the list of elements found in model that can be searched in the configuration tree.

   prepare(element => ...)
       Prepare the searcher to look for the element passed in the argument.  Returns the searcher object (i.e. $self).

   reset
       Re-initialize the search engine to redo the search from start

   searched
       Returns the searched element name.

Manual search
   next_step()
       Returns an array (or a ref depending on context) containing the next possible step to find the element you're looking for. The array ref
       can contain 1 or more elements.

       If the array ref is empty, you can get the target element with "current_object()".

   next_choice()
       Returns an array ref containing the next non-obvious choice to find the element you're looking for.

       If the array ref is empty, you can get the target element with "current_object()".

   choose( <chosen_element_name> )
       Tell the search engine your choice. The chosen element name must be one of the possibilities given by "next_step()".

   current_object()
       Returns the object where the search engine is. It can be a node, a list, a hash, or a leaf element.

Automatic search
   auto_choose ( element_callback, id_call_back)
       Finds the searched element with minimal user interaction.

       "element_callback" will be called when the search engine finds a node where more than one element can lead to the searched item.

       "id_call_back" will be called when the search engine finds a hash element or a list element which contain no or more than 1 elements. In
       this case the call-back will have return an id that will be used by the search engine to get the target element.

       Both call-back arguments will be:

       o   The current object (as returned by "current_object()")

       o   A list of possible choices

       For instances, your callback will be :

	my $id_cb = sub {
	   my ($object,@choices) = @_ ;
	   ....
	   return $choice[1] ;
	}

       Both call-back are expected to return a scalar value that is either:

       o   An element name

       o   An id valid for the list or hash element returned by "current_object()".

AUTHOR
       Dominique Dumont, (ddumont at cpan dot org)

SEE ALSO
       Config::Model, Config::Model::Node, Config::Model::AnyId, Config::Model::ListId, Config::Model::HashId, Config::Model::Value,

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