Data::Grove::Parent

NAME

Data::Grove::Parent − provide parent properties to Data::Grove objects

SYNOPSIS

use Data::Grove::Parent;
$root = $object−>root;
$rootpath = $object−>rootpath;
$tied = $object−>add_magic([ $parent ]);
$node = Data::Grove::Parent−>new($hash [, $parent]);
$node_list = Data::Grove::ParentList−>new($array [, $parent]);

DESCRIPTION

Data::Grove::Parent is an extension to Data::Grove that adds ‘"Parent"’ and ‘"Raw"’ properties to Data::Grove objects and methods for returning the root node of a grove, a list of nodes between and including the root node and the current node, and a method that creates parented nodes.

Data::Grove::Parent works by creating a Perl ‘‘tied’’ object that contains a parent reference (‘"Parent"’) and a reference to the original Data::Grove object (‘"Raw"’). Tying-magic is used so that every time you reference the Data::Grove::Parent object it actually references the underlying raw object.

When you retrieve a list or a property of the Raw object, Data::Grove::Parent automatically adds magic to the returned list or node. This means you only call ‘add_magic()’ once to create the first Data::Grove::Parent object and then use the grove objects like you normally would.

The most obvious use of this is so you don’t have to call a ‘"delete"’ method when you want to release a grove or part of a grove; since Data::Grove and Data::Grove::Parent objects have no cyclic references, Perl can garbage collect them normally.

A secondary use is to allow you to reuse grove or property set fragments in multiple trees. WARNING: Data::Grove currently does not protect you from creating your own cyclic references! This could lead to infinite loops if you don’t take care to avoid them.

METHODS

$object−>root()
$object−>rootpath()

‘"root()"’ returns the root node if ‘$object’ is a ‘"Data::Grove::Parent"’ object. ‘"rootpath()"’ returns an array of all the nodes between and including the root node and ‘$object’.

$tied = $object−>add_magic([ $parent ])

‘"add_magic()"’ returns a "Data::Grove::Parent" object with ‘$object’ as it’s ‘"Raw"’ object. If ‘$parent’ is given, that becomes the tied object’s parent object.

AUTHOR

Ken MacLeod, ken@bitsko.slc.ut.us