Data::Grove::Parent − provide parent properties to Data::Grove objects
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]);
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.
$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.
Ken MacLeod, [email protected]
perl(1), Data::Grove(3)